Grade
9 Chemistry
Title
The Building Blocks of Matter
Student
Teacher
MYP9: The Building Blocks of Matter Calendar
Week
Date
Activity
1
2
3
4
5
6
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MYP9: The Building Blocks of Matter AB Assessment – Using Polymers
The chemical industry converts raw materials, such as crude oil, natural gas, minerals, air and water, into useful products. The products include chemicals to use as dyes, food additives, polymers, fertilisers, paints and pharmaceutical drugs. The industry makes bulk chemicals on the scale of thousands or even millions of tonnes per year. Examples are ammonia, sulphuric acid, sodium, hydroxide, chlorine and ethane. Of particular interest are polymers. This category includes materials like all types of plastics (e.g. polythene, Perspex etc); types of rubber (such as latex) and materials for a huge range of everyday items like clothing (e.g. nylon, cotton, PVC and so forth). Lots of new materials are also polymers such as neoprene, Kevlar, Gore-Tex. The pie chart on the next page shows the range of products made by the chemical industry in the U.K. Your task is to; •
Research one type of polymer. You should aim to solve a particular problem or issue using this polymer.
•
Describe and discuss the problem or issue that needs to be solved.
•
Describe your chosen polymer,
•
Discuss how your choice of polymer can solve or help to address the problem or issue.
•
Discuss and evaluate the implications of using your polymer in solving the problem.
Your assessment should. •
Highlight the advantages and disadvantages of using your polymer to solve the problem or issue.
•
Use a mixture of text and graphical sources
•
Contain no more than 1200 words
•
Be fully referenced using the MLA format and contain a bibliography.
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Other specialities, 13.0
Synthetic fibres, 2.0
Plastics and synthetic rubber, 7.5
Fertilisers, 1.0
Basic organics, 12.0
Basic inorganics, 2.5
Dyes and pigments, 3.0
Agrochemicals, 3.0
Industrial Glass, 5.0
The Chemical Industry
Paints, varnishes and inks, 8.0
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Pharmaceuticals, 31.5
Soaps, toiletries and cleaning preparations, 11.5
MYP9: The Building Blocks of Matter
MYP9: The Building Blocks of Matter C Assessment
For the end of topic assessment you will need to revise; You will need to learn and understand the following topics: (in brackets are the pages in your textbook: ‘ Chemistry for You’) •
Atomic structure
•
Chemical bonding and properties of elements, compounds and mixtures
•
Formulae and equations
•
Reactivity series (pages 42-3, 52-3, 61, 70, 77 and 80)
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MYP9: The Building Blocks of Matter DEF Assessment - Reactivity
Scenario In this assessment of criteria DEF you will construct the reactivity series of given metals using displacement reactions. A simple diagram of a displacement reaction is shown below. You will be provided with metals and solutions of their sulphates: •
Copper and copper(II) sulphate
•
Tin and tin(II) sulphate
•
Magnesium and magnesium sulfate
•
Iron and iron(III) sulfate
•
Zinc and zinc(II) sulfate
Your task is; •
to plan and carry out an experiment to find out the reactivity series of the investigated metals using displacement reactions.
•
to explain and illustrate the order of reactivity by means of a model.
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MYP9: The Building Blocks of Matter Traffic Lights
â˜ş
No.
Question / Statement
1
I know the sub-atomic particles in an atom
2
I know what the atomic number represents.
3
I know what the mass number represents.
4
I know what isotopes are
5
I know the different types of bonds and their properties
6
I can describe and use the reactivity series
7
I can describe the properties and uses of alkanes
8
I can describe the properties and uses of alkenes
9
I can explain the process of the fractional distillation of crude oil
10
I can describe the uses of crude oil
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MYP9: The Building Blocks of Matter The Building Blocks of Matter
In this topic you will learn about; •
How atoms combine in different ways to make molecules of different substances.
•
Representing reactions using chemical equations.
•
The reactivity series and how to use it.
•
An introduction to organic chemistry and polymers.
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MYP9: The Building Blocks of Matter Burning Metals
It is important that scientists try to explain what happens in chemical reactions. Carry out the following experiment:
•
Set up the Bunsen burner
•
Use tongs to hold a piece of the first metal.
•
Examine the metal before holding it in the fire and write down your observations in the table below.
•
Hold the metal in the Bunsen burner flame until a reaction takes place
•
Copy the table below to write down your observations.
•
Repeat the experiment with the other metals
•
Switch off the gas
•
Write down your conclusions from your results.
Results Table. Metal
Observation before
Observation after
copper
magnesium
iron
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MYP9: The Building Blocks of Matter Atom, Molecule, Compound
Some definitions An atom is the smallest amount of a substance that there can be. For example, an atom of helium is the smallest unit of helium – it cannot be divided any further and still be called helium. An element is made of only one type of atom. For example, a piece of the element iron is made of only iron atoms. A compound is a group of elements that have reacted to form something new. For example, iron and oxygen react to form iron oxide – so iron oxide is a compound that contains the elements iron and oxygen. All chemicals are either in form of elements or compounds. The smallest amount of any element or compound is called a molecule. In the past you would have probably used the word particle instead.
Examples. Neon is usually a gas, consisting of single atoms. So a molecule of Neon is the same as one atom of Neon – three molecules of Neon gas are shown below (left). Oxygen is a gas, existing as pairs of atoms of oxygen – written O2. So a molecule of Oxygen gas is O2 - three molecules of Oxygen gas are shown below (centre). Water is a compound, written H2O – two atoms of Hydrogen and one atom of Oxygen. So a molecule of water is H2O – three molecules of water are shown below (right).
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MYP9: The Building Blocks of Matter Ionic Compounds
strong ionic bonds (electrostatic attraction between oppositely charged ions acting in all directions)
Properties of Ionic Compounds The ions in an ionic substance are packed together in a regular arrangement called a lattice. Due to the strong electrostatic forces ionic bonds are usually solids at room temperature A lot of energy is needed to separate the ions and melt the substance. Ionic substances have a high melting point and boiling point. They are usually hard substances. They usually dissolve in water because the water molecules are able to bond with the positive and negative ions which breaks up the lattice and keeps the ions apart. They usually cannot conduct electricity when solid because the ions are not free to move. However they usually conduct electricity when molten or in aqueous solution.
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MYP9: The Building Blocks of Matter Covalent Compounds
Compounds containing covalent bonds have molecules whose structures can be classified as either simple molecular or giant molecular.
Simple molecular structures are simple, formed from only a few atoms. (p 264-266) •
They have strong covalent bonds between the atoms within a molecule (intra-molecular) but weak bonds between the molecules (intermolecular bonds).
•
They have low melting points and boiling points because of the weak intermolecular forces of attraction.
•
Generally they do not dissolve in water. They are not charged and the water molecules are not attracted to them.
•
They do not conduct electricity because they do not contain ions.
Giant covalent structures contain many atoms joined by strong covalent bonds. •
They have high melting and boiling points
•
They are not soluble in water because the particles are not charged
•
They do not conduct electricity because there are no free ions ( graphite is an exception)
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MYP9: The Building Blocks of Matter Metallic Bonds
The final category we need to consider is a metallic bond. This type of bonding happens when we have a group of identical metal atoms together – for example a piece of iron or a lump of sodium. Remember that all metals want to lose their outer electrons and become positive ions. In a metallic bond, this is exactly what happens. Below is a diagram for sodium. There is a force of attraction between the positive ions and the free moving negative electrons – this is the metallic bond.
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MYP9: The Building Blocks of Matter Metallic Substances
The Properties of Metals (Metallic Bonds) •
Metals have high melting and boiling points because there are strong forces of attraction between the particles.
•
Metals are dense because the particles are packed closely together.
•
Metals conduct electricity due to the mobile ‘sea’ of electrons.
•
Metals are malleable and ductile. If a force is applied to a metal, rows of ions can slide over one another and the bonds reform.
•
Malleable: metals can be hammered into different shapes.
•
Ductile: metals can be pulled out into thin wires.
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MYP9: The Building Blocks of Matter Metallic Substances
Experiment: Close-packed structures
Arrange 4 pieces of wood in a square. You could use 4 books with a square hole between them. The size of the square depends upon the size and number of model metal atoms you can use. Your model atoms must all be the same size, just like a metal element (You can use marbles, table-tennis balls, polystyrene spheres, etc.). Fill the bottom of the square with model atoms. Make sure that there are no gaps. Now sit the second layer on top. Again, there should be no gaps. Now make a third layer. The atoms can sit in two possible positions, directly above the centres of the atoms in the first row, or with their centres not in line with the first row.
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MYP9: The Building Blocks of Matter Metallic Bonds
Try to make both structures. Both of these giant, close-packed structures are shown: a) For example, gold or copper (above) b) For example, zinc or nickel (below) Questions •
Do these explain why metals with these structures are dense?
•
Do they explain why metals have high melting points? Write down your explanations.
•
Do you know any metals which don’t have these properties?
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MYP9: The Building Blocks of Matter Bonding Summary
The properties of a substance describe how it behaves. The bonding in a substance (ionic, covalent or metallic) affects its properties. Here are some examples, but before we look at them, let us remind ourselves of the types of bonding.
Ionic bonding – opposite charges on the ions are attracted to each other.
Covalent bonding – atoms share electrons and form molecules.
Metallic bonding – atoms lose their outer electrons. The electrons then move freely between the ions, acting like a glue which attracts them.
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MYP9: The Building Blocks of Matter Bonding Summary
Appearance Metals look shiny in a way we all know. This shininess is called lustre and all metals have it unless they are in very small pieces (powder) or covered with an oxide coating. It is caused by the free electrons in the metal. Ionic and covalent compounds do not have lustre unless, for some reason, they also have free electrons.
Melting and Boiling points Ionic compounds have high melting points (over about 800ยบC usually) because the ions are strongly held together and it needs lots of energy to pull them apart. Covalent substances have low melting points because the forces between molecules are weak and so not much energy is needed to break them. Metallic substances usually have high melting points because the metal ions are held strongly together by their attraction for the electrons between them.
Electrical Conductivity A substance only conducts electricity if it has electrically charged particles that can move through it. Ionic substances have electrically charged particles - the ions. These are fixed in place when the ionic substance is solid (ionic solids do not conduct electricity), but become free to move if the ionic substance is melted or dissolved (so ionic liquids do conduct electricity). Remember it is the ions that carry the electricity in ionic liquids. Covalent substances have no free moving charged particles, so they do not conduct electricity. Metals have free moving electrons, so metals can conduct electricity when they are solid or liquid.
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MYP9: The Building Blocks of Matter Bonding Summary
Solubility a) In water. Water molecules have a dipole (water is a polar solvent) because the oxygen in H2O is slightly negative and the hydrogen is slightly positive. This helps water molecules to stick together.
Ionic substances can often dissolve in water because the water molecules can wrap around the separate ions allowing them to escape from each other. The charges on the ions mean that the water molecules can still stick together. Covalent substances stop the water molecules sticking to each other so the water tends to push them out. Covalent substances are less soluble in water than in non-polar solvents. Metals do not dissolve in water because the free electrons have nowhere to go. b) In non-polar solvents. Liquids like petrol do not have a dipole. The molecules have weak forces between them. Ionic substances do not easily dissolve in non-polar solvents because they get no help in separating from each other. Covalent substances can dissolve in non-polar solvents because their molecules can slide easily between the molecules of the solvent. Metals do not dissolve in non-polar solvents because neither the ions nor the electrons can escape.
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MYP9: The Building Blocks of Matter Bonding Summary
Hitting with a hammer (malleability) If an ionic substance is hit with a hammer, it breaks into pieces. It is brittle. Imagine what happens as the hammer pushes the ions down one row. Now + charges are next to + charges and – charges are next to – charges. The charges repel each other.
The weak forces between covalent molecules mean that they break easily. Covalent compounds are crumbly. When a metal is hit with a hammer, the ions in the metal are able to slide around each other and still stay stuck together, held by their attraction for the free electrons between them. This means metals can be shaped with a hammer. Metals are malleable.
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MYP9: The Building Blocks of Matter Diamond and Graphite
Structure of diamond
Strong covalent bonds
= carbon atom
Both diamond and graphite are forms of carbon. They have some special properties because of the way that the carbon atoms are arranged.
Structure of graphite strong covalent bonds within each layer
weaker forces hold the layers together
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MYP9: The Building Blocks of Matter Diamond and Graphite
Some non-metallic elements, especially carbon and silicon, have the ability to make bonds in all directions. The molecules can go on for millions and millions of atoms. Diamond is just carbon, the same stuff as in graphite or charcoal, but in diamond, every carbon atom is strongly held in place by four strong covalent bonds to other carbon atoms. Graphite is another form of carbon (different forms of the same element are called allotropes). In graphite, each carbon is joined to three other carbons to give a pattern of six-sided rings in flat layers. The forces holding the carbons are strong, but the forces between layers are weak. Free electrons are present which can move easily along the layers. Use the information on pages 258 to 261 to summarize the properties of diamond and graphite in a table like the one drawn below:
Properties of Diamond
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Properties of Graphite
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MYP9: The Building Blocks of Matter Word Match
Name
Description
Ionic
H2 Cl2 and CO2 are all examples of this type of bond
Giant (Network) Covalent
A group of reactive non metals such as Chlorine
Metallic
A negatively charged particle that orbits the nucleus of an atom
Simple (Molecular) Covalent
A central structure that can contain protons and neutrons
Ion
A structure in which there are positive ions surrounded by a “sea� of free electrons
Noble (Inert) gases
A reactive group of metals such as sodium
Halogen
Sodium chloride is an example of this type of bonding
Alkali Metal
Diamond, graphite and silicon dioxide are all examples of this type of strong bond
Nucleus
An atom that has either gained or lost electrons
Electron
A group of very unreactive gases such as Neon
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MYP9: The Building Blocks of Matter Checkpoint
What type of bonding would you expect in the following substances? Choose from; •
Ionic
•
Simple (molecular) covalent
•
Giant (network) covalent
•
Metallic
One has been done for you. Substance
Type of Bonding
Substance
Potassium Fluoride
Ionic
Chlorine
Type of Bonding
Silicon
Titanium
Carbon Dioxide
Silicon Oxide
Aluminium Oxide
Nitrogen Dioxide
Sulphur Oxide
Silver
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MYP9: The Building Blocks of Matter Spot the Bonding
Aim: To identify the type of bonding in wax, zinc and salt. Hypothesis: Because the type of bonding affects some of the properties of a material, we can look at these properties and use them to decide on the type of bonding. The properties are: Appearance - metallic substances have a metallic shininess (lustre), other substances do not have this kind of appearance. Melting point – metallic and ionic bonded substances have high melting and boiling points while covalent bonded substances have low melting and boiling points. Note – this is not true for some covalent giant structures such as graphite and diamond. Metals are malleable, while covalent substances are crumbly and ionic bonded substances are brittle. Metals conduct electricity when solid, but the other two types of bonding give solids that are insulators. Graphite is an exception. Metals do not dissolve in solvents unless they react with them though they will dissolve in mercury. Ionic substances dissolve better in water than in organic solvents. Covalent substances dissolve better in organic solvents than in water. When they are dissolved in water or melted, ionic substances are good conductors, covalent substances in water or melted are bad conductors.
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MYP9: The Building Blocks of Matter Spot the Bonding
Method: Carry out these tests on each of the 3 substances (wax, zinc and salt) Appearance: Look at the sample. Melting point: heat a sample of the substance in a crucible on a tripod, using a Bunsen burner. If the sample melts quickly (in a few seconds) then it has a low melting point. If melting takes a long time or does not happen, then the melting point is high. Put a sample in a mortar and try to crush or shape it with the pestle. Set up the circuit shown in the picture above (left)and touch the wires to the sample to see if it conducts electricity. If it conducts, the ammeter should show a current. Put a small sample into a test tube with about 5 cm3 of water and shake them together to see if it dissolves. Do the same thing using ethanol instead of water. If a substance can be melted or dissolved in water, try to pass an electric current through it using the apparatus shown above (right). Do the same with pure water first to compare the values. Note – substances that dissolve can be added to the water which is then stirred. To keep it a fair test, the distance between the wires and the amount (depth) they are in the water must be kept the same. This can be done by pressing them against the sides and bottom.
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MYP9: The Building Blocks of Matter Spot the Bonding
Copy and complete a results table like this one; Results
Test
wax
zinc
Test shows the bonding in each substance could be ....
salt
1 (look)
2 (melt)
3 (crush) 4 (conducts if solid?) 5 (solubility) 6 (conducts if liquid?)
Conclusions •
Once you have summarised your observations you will need to write your conclusions for this experiment.
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MYP9: The Building Blocks of Matter Revision
Bonding
Ionic
________________________________
Metallic
_____________ Structure
Simple molecular
Giant covalent
Giant metallic
Ionic
Melting Point
_____________
____________
High
High
Does it conduct electricity?
Not when ___________ but does when either molten or ____________ in water
_____________
_____________
______________
Sodium chloride
Zinc
Examples (below)
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MYP9: The Building Blocks of Matter Revision
Complete the tables below to give the formula of the compounds formed. Note: where the charge on the ion is 1+ or 1- the “1” has been left in for clarity.
Chloride Cl1Sodium Na1+
Bromide Br1-
Oxide O2-
NaCl
magnesium, Mg2+
Aluminium Al3+
Hydroxide OH1-
Nitrate NO31-
carbonate, CO32-
sulfate, SO42–
Sodium Na1+
Magnesium Mg2+
Aluminium Al3+ Ammonium NH41+
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MYP9: The Building Blocks of Matter More Complex Ions
Some ions contain more than one element. The common negative ions are: The ammonium ion, , is a common positive ion containing 2 elements. When working out the formula of compounds containing these ions, the same rule applies as with simple ions. The positive and negative charges on the ions must cancel each other out.
This is easy for a compound such as sodium nitrate. •
Sodium ions have a charge of 1+, Na1+
•
Nitrate ions have a charge of 1-, NO31-
•
Hence its formula is NaNO3
However, sometimes we need to use brackets if we have more than one of the complex ions. For example, what is the formula of magnesium nitrate? •
Magnesium ions have a charge of 2+, Mg2+
•
Nitrate ions have a charge of 1-, NO31-
•
Hence its formula is. Mg (NO3)2
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MYP9: The Building Blocks of Matter More Complex Ions
1. Work out the formula for these compounds - you will find the charges on the ions on page 391. •
potassium hydroxide
•
barium hydroxide
•
aluminium hydroxide
•
iron(II) nitrate
•
ammonium phosphate
•
lithium sulfate
•
calcium nitrate
•
copper(II) sulfate
•
iron(III) nitrate
•
iron(III) sulphate
2. Copy and complete the table below; Compound
Positive Ion
Negative Ion
Formula
Copper Oxide
Cu2+
O2-
CuO
Zinc sulphate Aluminium oxide Potassium hydroxide Calcium carbonate Sodium sulphate Barium chloride Silver nitrate
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MYP9: The Building Blocks of Matter How Many of Each?
How many atoms are there in each of the following compounds? How many different elements are there? One has been done for you.
Compound
H2S
Name
Number of atoms
Number of elements
Hydrogen sulphide
2xH + 1xS = 3
H, S = 2
CuSO4
Mg(OH)2
Al(NO3)2
MgSO4.7H2O
Magnesium sulphate heptahydrate
NaHCO3
C6H12O6
Glucose
KMnO4
Potassium permanganate
K2Cr2O7
Potassium dichromate
Al2(SO4)3
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MYP9: The Building Blocks of Matter A Balancing Act
H H O
O O
H H
H2O products (not enough O atoms)
H2 + O2 reactants
H H
O O
H2 + O2 (not enough H atoms)
H H O
H H O 2H2O
H H H H
O O
2H2 + O2
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H H O
H H O 2H2O
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MYP9: The Building Blocks of Matter A Balancing Act
Here are some rules for balancing equations: •
Count the atoms on each side of the equation.
•
If the number of each type of atom on either side is not the same, we have to balance the equation.
•
Put big numbers in front of the formula which contains atoms that do not balance.
•
(Never change the small numbers in a formula!)
•
Carry on until the atoms on each side of the equation are the same.
•
(Do this in pencil – you often have to change the numbers you put in first of all.)
Now try to balance these equations:
!"
#
!"
#
#
#
$
%
%
& ' (
&
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MYP9: The Building Blocks of Matter Displacement Reactions
Magnesium is more reactive than zinc, iron and copper. Therefore it can displace these metals. For example,
) " ) * ) " ) * !"
+
!"
+
Zinc has been displaced by magnesium.
The Thermit Reaction Would you expect aluminium to displace iron from its compounds? The reaction between aluminium and iron oxide gives out lots of heat. It is called the thermit reaction. (Your teacher might demonstrate this spectacular reaction.)
) )
#
2-
) )
-
2#
This displacement reaction has found a use in repairing railway tracks. The heat given out in the reaction melts the iron formed. The molten iron runs down between the tracks and welds them together.
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MYP9: The Building Blocks of Matter Reactivity Series Questions
1. Write word and symbol equations for any of the following pairs in which a displacement reaction will take place: a) zinc oxide + magnesium b) copper oxide + silver c) copper oxide + zinc d) iron(III) oxide + zinc.
2. Decide which of the pairs below will react. If they do react complete the word equations: a) zinc + copper oxide b) zinc + iron nitrate c) iron + magnesium oxide d) magnesium + copper sulfate e) copper + silver nitrate f)
copper + lead nitrate
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MYP9: The Building Blocks of Matter Reactivity Series Questions
3. Complete these word and symbol equations. Notice the use of state symbols (s), (l), (g) and (aq) – solid, liquid, gas and aqueous (in water);
magnesium
+
zinc oxide
Mg(s)
+
ZnO(s)
zinc
+
copper sulfate
Zn(s)
+
CuSO4(aq)
zinc
+
lead nitrate
Zn(s)
+
Pb(NO3)2(aq)
magnesium
+
iron nitrate
Mg(s)
+
Fe(NO3)2(aq)
magnesium
+
copper chloride
Mg(s)
+
CuCl2(aq)
lead
+
silver nitrate
Pb(s)
+
AgNO3(aq)
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MYP9: The Building Blocks of Matter Reactivity Series Questions
4. Look at these metals reacting with dilute hydrochloric acid: a) What is the gas given off? b) Complete this word equation: magnesium + hydrochloric acid
c) Draw 2 test-tubes, showing what happens when ; i)
zinc
ii)
copper
are added to dilute hydrochloric acid.
5. Explain these facts: a)
Gold, silver and platinum are used to make jewellery.
b)
Potassium, lithium and sodium are stored in jars of oil.
c)
Food cans are plated in tin, but not zinc.
d) Aluminium is quite high in the Reactivity Series, but can be used outdoors for things such as window frames.
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MYP9: The Building Blocks of Matter Reactivity Series Notes
The reactivity series is a list of metals. The metals are in order of reactivity, usually with the most reactive at the top. Reactive metals are metals that combine easily with other substances, often giving out lots of energy as they do. Once combined they are difficult to separate back. Unreactive metals are the opposite, they don’t combine easily and they are easy to separate from their compounds. Reactive metals can displace (replace) unreactive metals from their compounds. These differences work for nearly all reactions and so we can use the reactivity series to predict reactions. A reactivity series usually looks like this:
Most Reactive
Potassium Sodium Calcium Magnesium Aluminium Carbon-(not a metal but goes here for competition reactions with oxygen) Zinc Iron Hydrogen-(again this is strictly speaking not a metal, but metals above here can displace hydrogen from acids) Copper Silver
Least Reactive
Gold
Other metals can also go into the list, but these are the most common.
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MYP9: The Building Blocks of Matter Reactivity Series Notes
How do we know about Reactivity? Lots of reactions can be used to find out the order of reactivity of metals. Here are some of them.
Reaction with Cold Water Potassium melts and fizzes across the surface as it dissolves, giving hydrogen and a solution of alkaline potassium hydroxide. The hydrogen burns with a lilac flame. Larger pieces of potassium usually explode. . ) / . ) " Sodium reacts like potassium, but the hydrogen does not burn. The alkali is sodium hydroxide solution. Calcium sinks to the bottom and gives off a steady stream of hydrogen bubbles as it dissolves. The alkali is calcium hydroxide solution (lime water). None of the other metals on our list have an obvious reaction with cold water, though you get a few bubbles of hydrogen after leaving magnesium in water for about a week.
Reaction with Steam Metals like magnesium, zinc and iron will react when heated with steam. The reaction gives the metal oxide, not the hydroxide e.g. . ) / ' )( . ) " Aluminium would react, but this is because the oxide coating on the metal prevents the reaction from taking place.
Reaction with Dilute Acid All the metals above hydrogen on our list will react with dilute acid to give hydrogen as they dissolve. The higher up the list the metal is, the faster it reacts. A substance called a salt is left in the solution. * * " Sometimes e.g. with lead, the salt doesn’t dissolve and so it prevents the reaction from taking place.
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MYP9: The Building Blocks of Matter Reactivity Series Notes
Reaction with Air (Oxygen) Most metals will react with oxygen in the air to make the oxide. The reaction gets stronger (more heat and light are given off) as we go higher in the series. .. " .. We get more of a reaction with powders – iron turns to black iron oxide, but iron filings (powder) burn like sparklers.
Competition for Oxygen Metals higher in the series will take the oxygen from oxides of metals lower down e.g. when magnesium powder is heated with copper oxide, there is a flash of flame and we are left with magnesium oxide and copper. ) " ) ..
) " ) ..
Suppose we compare the metals magnesium, aluminium, zinc and iron by looking for this sort of reaction. We could put our results in a table like this. Metal oxide
Metal Magnesium
Aluminium
Zinc
Iron
Magnesium oxide Aluminium oxide Zinc oxide Iron oxide
Key: means a reaction was seen means no reaction was seen
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MYP9: The Building Blocks of Matter Reactivity Series Notes
Other Displacement Reactions If we put a piece of copper into a solution of silver nitrate, silver crystals grow on the copper and the solution slowly turns to the blue of copper nitrate. The copper has displaced the silver because it is more reactive. ..
0
..
0
Reactions like these can help us put the less reactive metals in order in our reactivity series.
Metals and history Reactive metals corrode easily. If we want something made of metal to last, we may have to pick an unreactive metal. Coins, jewellery, electric wires and water pipes are made of unreactive metals. Sometimes, we need the extra strength of a metal like iron, but then we have to protect it with paint or add expensive chromium to stop it rusting. The first metals found or made by people were unreactive ones like copper, silver and gold. People took many years before they could extract the more reactive metals. The copper and bronze ages came before the iron age and the very reactive metals (ending in – ium) were not discovered until Napoleon’s time. Metals below carbon can be extracted from their oxides by heating the oxide with coke (carbon from coal), but the higher ones need to be extracted using a process called electrolysis. You will study electrolysis in Grade 10.
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MYP9: The Building Blocks of Matter Revision Questions
1. A spaceman brings back a metal from space. When added to cold water it reacts very slowly, giving just a few bubbles every hour. Where would the metal go in our reactivity series?
2. I have 3 metals, dizzium, jazzium and poppium. Dizzium reacts with jazzium oxide, but does not react with poppium oxide. Put the three metals in order of reactivity.
3. In the museums of Vienna, you can see swords made from bronze (a mixture of copper and tin) and from iron. The bronze swords are much older. Which swords would you expect to have lasted better? Explain your answer.
4. Describe what happens when zinc reacts with dilute acid?
5. Rubidium is a metal like sodium and potassium, but it is a bit more reactive. What would you expect to see if a small piece of rubidium is put onto cold water?
6.
Use the table of results on the next page to put the metals A, B, C and D in order of reactivity (most reactive first) and then use your list to complete the table. Metal oxide
Metal A
B
C
D
A oxide B oxide C oxide D oxide
Key:
means a reaction was seen,
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MYP9: The Building Blocks of Matter Revision Questions
Flame
7. Nickel is more reactive than copper. a) Write a word equation to describe the reaction of nickel with copper nitrate solution. b) What changes would you see when silvery nickel is put into blue copper nitrate solution (nickel compounds are green)?
8. The picture shows a piece of magnesium being heated in steam. a) Write a word equation for the reaction that takes place and name the gas that is burning at A. b) Now write the symbol equation for this reaction. c) Calcium is more reactive than magnesium. What would be the effect of using calcium instead of magnesium?
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MYP9: The Building Blocks of Matter From a Model to the Nobel Prize
1996 was a big year for Harry Kroto. Not only was he knighted (Sir Harry!) but he also received the Nobel Prize for Chemistry. Harry was born in 1939 in Wisbech (Cambridgeshire), brought up in Bolton (Lancashire) and went to university in Sheffield (Yorkshire). After finishing his PhD, he went on to do research in Canada and the USA. He arrived at Sussex University in 1967 and was made a professor in 1985. Harry enjoys pioneering projects at the cutting edge of science, often at the boundaries of several disciplines, for example, studying the chemistry of materials in space using radio-astronomy. He discovered long chains of carbon atoms in inter-stellar space and set about re-creating the conditions in which they were made in the lab. In these experiments he noticed a substance formed that was made of C60 molecules. Working with colleagues at Rice University, Texas, the problem of how 60 carbon atoms could be arranged in a molecule proved to be a fascinating puzzle. The problem was solved as shown below and Kroto, Smalley and Curl were awarded the Nobel Prize for their brilliant research. Sir Harry’s research will bring great benefits as the new family of carbon molecules, called fullerenes, are developed for new and exciting applications. However, Harry is worried by the government’s approach to funding research in Britain. He has said, “UK funding is so weak and short-term. Fundamental science will flounder and disappear if we aren’t careful. We’ve still got imaginative people, but we can’t afford the expensive equipment they need. The problem is not a lack of money but a lack of priority for research. It’s fairly obvious that the British government has made the decision that R & D (Research and Development) is not worth it. There is money around but it prefers to spend it on replacing £80 million tornado jet fighters.” Sir Harry also criticises industry in the UK for having no interest in long-term developments. He blames leaders of industry, who tend to be lawyers and accountants, in contrast to the scientists and engineers who progress to top management positions in Japanese companies
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MYP9: The Building Blocks of Matter Graphene – The Next Big Thing?
The material graphene was touted as "the next big thing" even before its pioneers were handed the Nobel Prize last year. Many believe it could spell the end for silicon and change the future of computers and other devices forever. Graphene has been touted as the "miracle material" of the 21st Century. Said to be the strongest material ever measured, an improvement upon and a replacement for silicon and the most conductive material known to man, its properties have sent the science world - and subsequently the media - into a spin. Graphene is taken from graphite, which is made up of weakly bonded layers of carbon. Graphene is composed of carbon atoms arranged in tightly bound hexagons just one atom thick. Three million sheets of graphene on top of each other would be 1mm thick. The band structure of graphite was first theorised and calculated by PR Wallace in 1947, though for it to exist in the real world was thought impossible. Due to the timing of this discovery, some conspiracy theorists have linked it to materials at the Roswell "crash site" made famous by UFO enthusiasts. In 2004, teams including Andre Geim and Konstantin Novoselov demonstrated that single layers could be isolated, resulting in the award of the Nobel Prize for Physics in 2010. It is a good thermal and electric conductor and can be used to develop semiconductor circuits and computer parts. Experiments have shown it to be incredibly strong. "Our research establishes graphene as the strongest material ever measured, some 200 times stronger than structural steel," mechanical engineering professor James Hone, of Columbia University, said in a statement. And the way this material can be utilised is as surprising as its properties. "Graphene does not just have one application," says Professor Andre Geim, the current co-holder of the Nobel Prize in physics for his work with the material at Manchester University. "It is not even one material. It is a huge range of materials. A good comparison would be to how plastics are used." And the benefits to both businesses and to the consumer are obvious - faster and cheaper devices which are thinner and flexible. "You could theoretically roll up your iPhone and stick it behind your ear like a pencil," Professor James Tour, of Rice University, told the Technology Review.
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MYP9: The Building Blocks of Matter Organic Chemistry
Organic chemistry is the chemistry of carbon based compounds. This is an extremely significant category of chemicals. All living things (like you) and substances made from things that were living (such as coal, crude oil and natural gas) are organic compounds. Remember that Carbon ( C ) is in Group IV of the Periodic Table, so it forms four (covalent) bonds with other chemicals, like Hydrogen. Organic compounds that are made of only carbon and hydrogen are called Hydrocarbons. Look at the hydrocarbon molecules shown in the pictures, which show 3 of the simplest possible hydrocarbons. Notice that there are four “single bonds� for each carbon atom and that each hydrogen atom has one single bond.
These are the first 3 in a series of related compounds called alkanes. The first one is called methane and has a formula CH4. The second alkane has a formula of C2H6. It could also be written as CH3-CH3 or just CH3CH3. These alternative ways of writing the alkane are very useful because they give more information about the structure of the substance. In the same way the third alkane would normally be given the formula C3H8. It can also be written as CH3-CH2-CH3 or just CH3CH2CH3.
Exercise. What is the structure and formula for the next member of the alkane family (butane, containing 4 carbon atoms)? How can the formula also be written?
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MYP9: The Building Blocks of Matter Alkanes
Many of the alkanes are common compounds. For example methane is used in Science laboratories in Bunsen burners and Propane is used as camping gas. Complete the table for the first 10 alkanes below and deduce the general formula for an alkane containing N carbon atoms. Name
Number of Carbons
Formula
Methane
1
CH4
Ethane
2
C2H6
Propane
3
C3H8 C4H10
Butane Pentane Hexane Heptane Octane Nonane Decane ----
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N carbons
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MYP9: The Building Blocks of Matter Alkanes
We can keep adding extra carbon atoms to get longer and longer alkane compounds. However, when we get to Butane (4 carbon atoms and 10 hydrogen atoms), we can also begin to arrange them in different ways, like this:
And like this:
The middle carbon is now attached to 3 other carbons. These are different molecules with the same formula (C4H10) are called isomers.
Exercise Try drawing some isomers of pentane ( C5H12) yourself. Note: the molecule shown below is not a new isomer, it still has 4 carbons in a line, we have simply bent the molecule round.
The alkanes are known as saturated hydrocarbons because all of the available bonds to carbon atoms are occupied with hydrogen atoms. They are relatively unreactive, apart from combustion with oxygen. For this reason they are common fuels. Methane gas is used for cooking (and in Science laboratories). Propane and Butane are used as camping gas. Larger compounds like octane are present in petrol used in cars and motorcycles.
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MYP9: The Building Blocks of Matter Combustion of Alkanes
All alkanes will burn in oxygen to produce carbon dioxide and water. Question 1 Balance these equations for the combustion of some alkanes. CH4
+
O2
CO2
+
H2O
C2H6
+
O2
CO2
+
H2O
C3H8
+
O2
CO2
+
H2O
C4H10
+
O2
CO2
+
H2O
Question 2 What would the products be if there was insufficient oxygen for complete combustion?
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MYP9: The Building Blocks of Matter Crude Oil
Oil that we get from the ground, in oil wells, is called crude oil. It is a mixture of lots of different alkanes – from 1 carbon atom (CH4) to over 70 carbon atoms. In order to make use of crude oil it first needs to be separated into groups of similar compounds and this process is called fractional distillation. This process is summarised below. Crude oil is heated up to high temperatures, causing most of the alkanes in the crude oil to boil. This boiling mixture enters the base of the fractionating column. The gases formed rise up and so cool down. Compounds with more carbon atoms condense sooner while the lighter compounds rise further up the column. In this way groups of alkanes with a similar number of carbon atoms, or fractions, can be collected.
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MYP9: The Building Blocks of Matter Crude Oil
Make a table like the one shown below to summarise the uses of the various fractions of crude oil. Useful sites for your research might include; http://www.bbc.co.uk/schools/gcsebitesize/science/aqa_pre_2011/rocks/fuelsrev1.shtml http://www.chemguide.co.uk/organicprops/alkanes/background.html#top
Name of Fraction
Number of Carbons
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Description & Uses
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MYP9: The Building Blocks of Matter Cracking
In the fractional distillation process, many of the alkanes that are obtained are long chains – such as those in the lubricating oil, fuel oil and bitumen fractions. In order to make these long chained hydrocarbons more useful they can be cracked into smaller compounds. The cracking of alkane hydrocarbons involves thermal decomposition. This means that the large hydrocarbon molecules break into smaller molecules when they are heated. The hydrocarbons are boiled and the hydrocarbon gases are passed over a hot powdered aluminium oxide (Al2O3) catalyst. The catalyst works by providing a good surface for the cracking to take place.
Example 1 Decane is an alkane containing 10 carbon atoms (C10H22). This can be cracked to produce a smaller alkane called octane (C8H18) and a second product, ethene (C2H4). This last compound belongs to a different series called the alkenes and is itself a very useful chemical. C10H22
C8H18
+
C2H4
Notice that the equation balances automatically. Octane is used in petrol and ethene is used to make polymers.
Example 2 Hexane can be cracked to give ethene and one other product. Write a balanced equation for this reaction. Name the other product. Identify any saturated hydrocarbons in your reaction.
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MYP9: The Building Blocks of Matter Alkenes
H
H
H
C
C
C
C
C
H
H
H
H
H
H
H
A second series of related hydrocarbons is obtained if we include one double bond between two of the carbon atoms. The simplest possible arrangement is shown on the left (notice that the simplest arrangement must have two carbon atoms) and is called ethene. The formula for ethene is C2H4. The next simplest arrangement, with three carbon atoms, is shown on the right and is called propene. The formula for propene is then C3H6. The series of chemicals that are formed by adding more carbons is called the alkenes. Notice the similarity of names compared to the alkane family. The difference is that all alkenes have names ending in –ene. As before we can also write the formulas for these alkenes in different ways. For example, the simplest alkene is ethene and is usually written as C2H4. We could also write this as CH2-CH2 or just CH2CH2. The next alkene in the series is propene, normally written as C3H6. We could write this to give more information as CH2-CH-CH3 or just CH2CHCH3.
Exercise. What would be the structure of the next alkene, butene, containing 4 carbon atoms?
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MYP9: The Building Blocks of Matter Alkenes
One of the most significant uses of alkenes is to make polymers. These are amazingly common in just about every aspect of our lives today. Two examples are shown above – plastic bags are made from the polymerisation of ethene (to make poly(ethene) – usually called polythene) and other items like plastic folders are made from the polymerisation of propene (to make poly(propene) – usually called polypropylene). Complete the table below for the first few alkenes and deduce the general formula for an alkene containing N carbon atoms. Name
Number of Carbons
Formula
Ethene
2
C2H4
Propene
3
C3H6
Butene
4
C4H8
N carbons
?
Pentene Hexene Heptene Octene ----
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MYP9: The Building Blocks of Matter Alkenes
H
H
C
H
CH3
H
C
C
H
C
C
H
H
H
C2H5
H
C
H
You can draw alkenes in the usual way. However, one particularly useful way of drawing them is shown above, which shows ethene (left), propene (middle) and butene (right). What has happened is that everything that comes after the second carbon atom has been placed together. This has the effect of making them all look similar, which will very useful when we look at polymerisation. Alkenes are more reactive than their alkane cousins – ethene is more reactive than ethane for example. This is because, in a reaction, the double bond may “break” and so allow a wider variety of combinations with other chemicals. Examples. The reaction of ethene with hydrogen can be written as; C2H4
+
H2
C2H6
And the reaction of ethene with chlorine could be written like this; CH2-CH2
+
Cl2
CH2Cl-CH2Cl
Exercises; Balance these reactions for the combustion of ethene and propene. C2H4
+
O2
CO2
+
H2O
C3H6
+
O2
CO2
+
H2O
C4H8
+
O2
CO2
+
H2O
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MYP9: The Building Blocks of Matter Polymerisation
H
n
H
C
H
C
C
H
H
H
C
H
H
n n x ethene monomers
1 x poly(ethene ) polymer, n units long
The unique nature of alkenes – having a double bond between two of the carbon atoms – turns out to be very significant. In particular, it allows the possibility of making polymers. A polymer is formed when thousands of monomers (of a particular alkene) add together to make one very long molecule. One of best examples of this would be the addition of thousands of ethene molecules (the monomers) to make one poly(ethene) – or polythene – molecule. Polythene is the material that plastic bags are made of – like those you find at a supermarket. The reaction of ethene by addition polymerisation to make polythene is represented above. The n in the reaction represents a very large number, typically thousands. What happens is that the double bond in ethene unfolds, as shown in the diagram at the bottom. This makes two more connections available for each molecule, which are used to join to each other in one very long chain.
H
C
H
H
H
H
C
C
H
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H
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MYP9: The Building Blocks of Matter Polymerisation
C6H5
H
C
C
H
H
Example The monomer styrene is used to make the polymer poly(styrene), often referred to as Styrofoam. The monomer is represented by the drawing above. a) Styrene undergoes addition polymerisation to form polystyrene. Represent the reaction of styrene to form polystyrene. Shown below. b) Give one use of polystyrene. For packaging electronic goods. c) Give one harmful effect that polystyrene can have on the environment. Polystyrene is not biodegradable. This can cause problems if it is not re-used or recycled. It could be burned to release energy but this may result in the production of toxic chemicals.
C6H5
H
n
C
H
C6H5
H
C
C
H
C
H
H
n
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MYP9: The Building Blocks of Matter Organic Chemistry Checklist
a) The bonding of carbon – remember each carbon forms 4 bonds, each hydrogen forms 1 bond and each oxygen forms 2 bonds. E.g. H H
O
C
b) Isomers (different arrangements of the same atoms in a molecule) e.g. show the different isomers of pentane C5H12. c) Saturated (no double or triple bonds) and unsaturated (at least one double or triple bond) e.g. alkanes are saturated and alkenes are unsaturated. d) Homologous series (a group of compounds with the same general formula, the same chemical properties and a steady change in some physical properties such as boiling point). e) The members of a homologous series have the same functional group e.g. the C=C double bond in alkenes and the –OH group in alcohols. f)
Alkanes – you need to know their general formula – CNH2N+2 You need to know their names up to C10H22 (methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane). You need to know why they are relatively unreactive – in order to react, they must break strong C-C and C-H bonds.
g) Revise the fractional distillation of crude oil, how it works and the way their different boiling points allows us to separate them, ways in which the fractions differ plus uses for some fractions. h) Be able to write and balance equations for combustion (burning, reacting with oxygen). i)
Be able to describe cracking (using heat and/or catalysts to turn bigger less useful molecules into smaller, more valuable ones). Remember, cracking always produces unsaturated compounds.
j)
Alkenes – you need to know their general formula – CNH2N You need to know their typical reaction – addition to the double bond; The test for alkenes – they decolourise bromine water from orange/brown; preparing alkenes – see cracking; making polymers (like plastics) from alkenes and other unsaturated compounds.
k) Advantages and problems caused by the use of plastics and crude oil.
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MYP9: The Building Blocks of Matter Practice Question 1
Propane and ethene are both important hydrocarbons.
propane formula
ethene
C3H8 H
H C
structure
C
H
H
a) Copy and complete the table by adding the formula of the ethene molecule and the structure of the propane molecule. b) Propane is a fuel used in camping stoves. When propane burns there is an exothermic reaction. What is meant by the term “exothermic reaction�? c) Balance the chemical equation for the reaction which takes place when propane burns in a plentiful supply of air. d) C3H8
+
O2
CO2
+
H2O
e) Ethene can be changed into a plastic. The equation shown below represents the reaction in which ethene is polymerised.
n
f)
H
H
H
H
C
C
C
C
H
H
H
H n
What is the name of the plastic formed in this reaction? f)
What type of polymerisation reaction is shown in the equation?
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MYP9: The Building Blocks of Matter Practice Question 2
To make crude oil more useful it is separated into different fractions.
Refinery gas 40°C Petrol 110°C
180°C
Kerosene
260°C
Gas oil
350°C
Crude oil
Fuel oil
400°C
Over 400°C
Heat
Complete the gaps in the following sentences. a) Crude oil is separated into different fractions by a process called .............................................. ……………................................... . Each fraction has a different ............................................... Each fraction is a mixture of compounds. Most of these compounds are hydrocarbons, made up of the elements hydrogen and carbon. b) Explain the difference between a mixture and a compound. c) Explain the difference between a compound and an element.
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MYP9: The Building Blocks of Matter Practice Question 3
One reason the oil industry is important is that it uses crude oil to produce many of the plastic materials we use in everyday life. a) The first stage in the formation of a plastic material is called cracking. Butane (C4H10) a hydrocarbon in crude oil, can be cracked to produce two different hydrocarbons, ethane (C2H6)) and ethene (C2H4) For cracking to happen what needs to be done to the hydrocarbon? b) Copy and complete the equation for the cracking of butane using displayed formulae.
H
H
H
H
H
C
C
C
C
H
H
H
H
+
H
Butane (C4H10)
Ethane (C 2 H 6 )
Ethene (C 2 H 4 )
c) Copy and complete the balanced chemical equation far the complete combustion of ethane in oxygen. C2H6
+
…………………..
…………………….
+
…………………….
d) The second stage is the formation of the plastic material by polymerisation. e) Describe how ethene (C2H4) forms poly(ethene). You do not need to give the reaction conditions or the names of catalysts.
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MYP9: The Building Blocks of Matter Practice Question 4 & 5
Question 4 The diagram shows a reaction which takes place in an oil refinery.
H
H
H
H
H
H
H
C
C
C
C
C
C
H
H
H
H
H
H
H
Compound X
H
H
H
H
H
H
C
C + H
C
C
C
C
H
H
H
H
H
H
Compound Y
H
Compound Z
a) X, Y and Z are all examples of which type of compound? b) What type of chemical reaction takes place when compound X is converted into compounds Y and Z? c) Compounds Y and Z are both useful substances. Compound Y is unsaturated. Compound Z is saturated. Explain what is meant by the terms “saturated” and “unsaturated”. d) Suggest one use for compound Y. e) Suggest one use for compound Z.
Question 5 Crude oil consists of a large number of different compounds. Most of these compounds are alkanes. f)
Explain how fractional distillation separates crude oil.
g) What are alkanes? h) Alkanes, such as methane, CH4, are used as fuels. i)
Write a balanced chemical equation for the complete combustion of methane in oxygen.
j)
Alkenes can be made by cracking large alkane molecules.
k) Explain how the cracking process is carried out. l)
Give a chemical test which would show the difference between an alkene and an alkane
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MYP9: The Building Blocks of Matter Practice Question 6
The label has been taken from a tube of Humbrol Polystyrene Cement, a glue used in model making.
HUMBROL Polystyrene Cement Paint product contains 1.1.1 TRICHLOROETHANE • Keep container tightly closed. HARMFUL
Harmful by inhalation, in contact with skin and if swallowed. Avoid contact with eyes. Keep out of reach of children.
• For use on all polystyrene plastic except expanded or foam. Specially recommended for plastic kits. Thinly coat each surface, press together. To remove cement from fabrics use Humbrol Universal Cleaner.
HUMBROL LTD., HULL, ENGLAND.
The solvent used is 1,1,1-trichloroethane. The structural formula of this molecule is:
Cl
Cl
H
C
C
Cl
H
H
a) What do the lines between the atoms represent? b) State whether 1,1,1-trichloroethane is saturated or unsaturated. Give one reason for your answer. c) 1,1,1-trichloroethane is being replaced in favour of a ‘better’ solvent. Use information on the label to help you to suggest why.
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MYP9: The Building Blocks of Matter Practice Question 7
Polystyrene is a plastic. Plastics are polymers which are made by the process of polymerisation. a) What is meant by polymerisation?
b) The table gives information about monomers and the polymers made from them. Complete the table.
POLYMER
MONOMER name ethene
formula H
name
formula H H
H C
C
H
H
styrene
polystyrene
C
C
H
H
H
H
C
C
H chloroethene
H
H C
H
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n
C 6H 5 n
poly(chloroethene)
C Cl
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MYP9: The Building Blocks of Matter Practice Question 8
Ethene is the starting material for two plastics, poly(ethene) and PVC. a) Give one use for each of these plastics. Poly(ethene) PVC b) Crude oil is a mixture of many compounds. Most of the compounds consist of molecules made only of carbon and hydrogen. Choose one word from the list below to complete the sentence. carbohydrates
carbonates
hydrocarbons
hydrogen-carbonates
What name is given to compounds made only of carbon and hydrogen? c) The fractions contain molecules with similar numbers of carbon atoms. The main fractions are shown in the table below.
NAME OF FRACTION petroleum gases gasoline naphtha kerosene diesel oil lubricating oil residue
NUMBER OF CARBON ATOMS IN MOLECULES 1 to 4 4 to 12 7 to 14 11 to 15 14 to 19 18 to 30 more than 30
Naphtha burns more easily than diesel oil. Explain why.
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MYP9: The Building Blocks of Matter Practice Question 9
Propane is a small, hydrocarbon molecule and it is used as a fuel.
H
H
H
H
C
C
C
H
H
H
H
Propane molecule
Propane gas
a) Complete the sentences by choosing the correct words from the box. carbohydrate
high
hydrogen
hydroxide
low
volatile
Propane is a hydrocarbon with a ................................................................ boiling point. Propane is a hydrocarbon because it is made of ........................................................ and carbon only. b) Describe, in as much detail as you can, what happens when propane burns.
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MYP9: The Building Blocks of Matter Practice Question 10
Crude oil is a complex mixture of hydrocarbons, mainly alkanes. The number of carbon atoms in the molecules ranges from 1 to over 100. a) How does the boiling point change as the number of carbon atoms in the molecules increases? b) Name the method used to separate petroleum into fractions. c) The simplest hydrocarbon is methane, CH4. Its structure can be represented: H H
C
H
H
d) Draw the structure of ethane, C2H6. e) Large hydrocarbon molecules are less useful as fuels. They can be broken down to give smaller molecules. Some of these smaller molecules are unsaturated. The simplest of these is ethene, C2H4. Name the process used to break down large hydrocarbon molecules. f)
Draw the structure of ethene, C2H4. Why is ethene said to be unsaturated?
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MYP9: The Building Blocks of Matter Practice Question 11
Cracking is an important process in the oil industry. The equation below shows the cracking of a hydrocarbon compound into two different compounds, A and B.
H
H
H
H
H
H
H
C
C
C
C
C
C
H
H
H
H
H
H
H
H
H
H
H
H
C
C + H
C
C
C
C
H
H
H
H
H
H
H
Compound A
H
Compound B
a) State two differences between the structures of compounds A and B.
b) Name compounds A and B
c) Why is compound A useful in industry?
d) Alkanes and alkenes are obtained from crude oil.
What method is used to separate crude oil into its components?
e) The box contains the names of five components that can be separated from crude oil diesel
fuel oil
paraffin
petrol
propane gas
Write the list in order of increasing boiling point, starting with the lowest boiling point.
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MYP9: The Building Blocks of Matter Practice Question 12
Read the following information.
Landfill, Incineration, Recycling and Re-use of Poly(ethene)
People could be encouraged to re-use their poly(ethene) bags and containers.
Recycling poly(ethene) saves raw materials and energy needed to make new plastic. When polymers are recycled the plastics must be collected, transported, sorted into different types by hand and washed. This requires the use of fossil fuels and is expensive.
Poly(ethene) can be burnt in an incinerator with other household waste. The heat released could be used to make steam to drive an electric generator. Surplus heat could be used to heat greenhouses used for growing vegetables. Incineration at too low a temperature can produce harmful substances. The residue (ash) has to go to landfill.
Landfill is probably the easiest way to dispose of polymers and it is cheap. Polymers are often mixed in with other household rubbish. Household waste does not get sorted into different materials because it is disposed of in the same hole in the ground. When the hole is eventually full, the waste is covered by a layer of soil to stop it smelling. The waste gets compressed under its own weight. Most polymers, such as poly(ethene), are not biodegradable so will remain in the ground forever.
You are asked to decide which option for the disposal of poly(ethene) will be put forward in your area. You decide that recycling is the best option. Suggest one economic argument and one environmental argument that will be made against recycling.
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MYP9: The Building Blocks of Matter Organic Revision 1
Cracking is used in the oil industry to break large hydrocarbon molecules into smaller molecules.
Small molecules out
Reactor vessel containing catalyst
Large molecules in Cracking involves a thermal decomposition reaction. a) State what must be done to make a thermal decomposition take place. b) Suggest why air must be excluded from the reactor vessel. The equation shows a reaction that can take place in the reactor vessel. A nonane molecule is split into two smaller molecules. c) Complete the equation by adding the formula of the other product. C9H20
………………………………….. +
C2H4
The product with the formula C2H4 is called ethene. Some ethene is reacted with steam. The equation represents this reaction. C2H4
+
H2O
C2H5OH
d) Name the useful product with the formula C2H5OH.
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MYP9: The Building Blocks of Matter Organic Revision 2
Modern window frames are often made from uPVC plastic which contains the polymer called poly(chloroethene).
+
WONDERFUL WINDOWS Replace your old wooden windows with our superb high quality uPVC windows! NO PAINTING - MAINTENANCE FREE
a) State why plastic window frames need no painting or maintenance. b) Name the monomer that is used to make poly(chloroethene). c) Explain what is meant by the term polymer. d) Give one disadvantage of using a polymer for window frames. e) The monomer used for making the polymer uPVC is often called vinyl chloride. It has a structure that is similar to ethene except that one of the hydrogen atoms in ethene is substituted by a chlorine atom. Draw structures to represent ethene and vinyl chloride.
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MYP9: The Building Blocks of Matter Organic Revision 3
The diagram shows an apparatus that can be used to carry out cracking reactions in a laboratory. Paraffin soaked onto mineral wool Aluminium oxide or broken porcelain Delivery tube
B Warm
Strong heat
A
Cold water
a) Why is aluminium oxide or broken porcelain used? b) Paraffin contains decane. The cracking of decane can be represented by the equation below. A decane molecule is split into two smaller molecules. c) Complete the equation by adding the formula of the other product. C10H22
……………………………………..
+
C2H4.
d) Would you expect C2H4 molecules to collect at position A or B shown on the diagram? Explain your answer. e) Explain, as fully as you can, why cracking is used in the oil industry. f)
The cracking reaction produces a mixture of products. The mixture contains hydrocarbons with different boiling points.
g) Suggest a method of separating this mixture.
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MYP9: The Building Blocks of Matter Organic Revision 4
a) Propene and propane can be produced from crude oil. A propene molecule (C3H6) can be represented by the structure shown below.
H C
H
H
C
C
H
H
H
Draw a similar diagram to show the structure of a propane molecule (C3H8) b) Which molecule, propene or propane, is unsaturated? Give a reason for your answer c) The equation below represents the polymerisation of propene.
H
H
H
H
n C
C
C
C
H CH 3
H CH 3 n
Name the polymer produced by this reaction. d) Explain the meaning of the term polymerisation. e) Describe the problems caused by the everyday use of this polymer.
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MYP9: The Building Blocks of Matter Cross Word
Across
Down
1. a poisonous gas in group 7
2. the correct name for water
5. a form of carbon used as a lubricant
3. a precious form of carbon
8. formed from one carbon atom and two oxygen atoms
4. all of the elements organised in their groups
9. the smallest amount of any element
6. a substance made when a metal and a nonmetal react
10. a heavy metal that is a liquid at room temperature 11. a substance made when two or more elements combine in a chemical reaction
G9 Chemistry - The Building Blocks of Matter Jun2013
7. a very reactive metal in group 1
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MYP9: The Building Blocks of Matter Word Search R
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ATTRACTION
CHEMICAL REACTION
COMPOUND
COVALENT
DOUBLE BOND
ELECTRON
ELEMENT
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METALLIC
MIXTURE
MOLECULE
NEUTRON
NUCLEUS
ORBIT
PERIODIC TABLE
PROTON
REACTIVITY
SHELL
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MYP9: The Building Blocks of Matter Traffic Lights
â˜ş
No.
Question / Statement
1
I know the sub-atomic particles in an atom
2
I know what the atomic number represents.
3
I know what the mass number represents.
4
I know what isotopes are
5
I know the different types of bonds
6
I know properties of the different bonds
7
I can write formulae of compounds
8
I can name chemical compounds
9
I know about reactivity series
10
I know benefits and limitations of using models
11
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MYP9: The Building Blocks of Matter Self Reflection What activities helped me learn best?
What activities could be improved?
Are there any activities that you think should be included?
Your comments on the assessments in this unit (AB, C and DEF)
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MYP9: The Building Blocks of Matter Learner Profile
In this Unit where did you get the opportunity to develop being
I asked questions or performed research about…
Inquirer I showed my understanding and knowledge when …
Knowledgeable I had to think a lot about….
Thinker I communicated best when…
Communicator I showed I was fair when….
Principled I accepted different points of view when…
Open-minded I looked after my classmates and/or the environment when…
Caring I was nervous about….
Risk taker I felt most positive in this unit when….
Balanced I learned best when I …
Reflective
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