C1.8a What’s the equation? 1
Cut out the cards.
2
Sort them into reactants (cards with a shaded background) and products (white background).
3
Arrange the cards to match the correct reactants with the correct products.
calcium carbonate
+
carbon dioxide
copper carbonate
+
carbon dioxide
zinc carbonate
+
carbon dioxide
calcium oxide
copper oxide
zinc oxide
→
→
→
1
Cut out the cards.
2
Sort them into reactants (cards with a shaded background) and products (white background).
3
Arrange the cards to match the correct reactants with the correct products.
calcium carbonate
+
carbon dioxide
copper carbonate
+
carbon dioxide
zinc carbonate
+
carbon dioxide
calcium oxide
copper oxide
zinc oxide
→
→
→
© Pearson Education 2010. Edexcel GCSE Science Activity Pack. This document may have been altered from the original.
C1.8b Formulae
calcium carbonate CaCO3
C (carbon)
three
calcium oxide CaO
Na (sodium)
one
carbon dioxide CO2
H (hydrogen)
two
sodium carbonate Na2CO3
O (oxygen)
one
sodium oxide Na2O
Ca (calcium)
Water H2O
1
Cut out the cards.
2
Do the following for each name and formula card: ●
Put the name and formula card on the table.
●
Work out from the formula which atoms the substance contains. Put the cards with the names of these atoms next to the formula card.
●
Work out from the formula how many of each atom the substance contains. Put the cards with the number of each atom next to the names of the atoms.
●
Write down the name of the substance, its formula, and the names and number of each atom it contains.
●
Use the cards again to work out the next substance.
Example water H2O
H (hydrogen)
two
O (oxygen)
one
Water (H2O) contains two hydrogen atoms and one oxygen atom.
© Pearson Education 2010. Edexcel GCSE Science Activity Pack. This document may have been altered from the original.
C1.8c Balancing equations 1
Cut out the cards.
2
Sort them into reactants (cards with a white background) and products (shaded background).
3
Arrange the cards to match the correct reactants with the correct products.
4
Copy the words into your book, adding arrows to complete the word equations.
H5 Copy the formulae into your book, adding arrows as needed, then add numbers to balance any unbalanced equations.
calcium oxide
water +
potassium bromide
silver nitrate +
CaO
H2O
KBr
AgNO3
lead nitrate
potassium iodide
calcium hydroxide
carbon dioxide
KI
Ca(OH)2
+ Pb(NO3)2 sodium carbonate
calcium carbonate
Na2CO3
CaCO3
calcium oxide
carbon dioxide
calcium hydroxide
CaO
CO2
Ca(OH)2
sodium oxide
carbon dioxide
lead iodide
+ CO2
+
+
potassium nitrate +
Na2O
CO2
PbI2
KNO3
potassium nitrate
silver bromide
calcium carbonate
water
+ KNO3
AgBr
Š Pearson Education 2010. Edexcel GCSE Science Activity Pack. This document may have been altered from the original.
CaCO3
+ H2O
C1.8d Writing balanced equations This explains how to balance equations, starting with the word equation.
1
2
3
4
5
6
Step Write down the word equation Write the correct formula for each substance underneath their names in the word equation. Leave space either side of each formula. Check to see if it is already balanced. If it is not balanced, choose an element with different numbers of atoms on each side of the equation. Add a whole number to the front of one of substances containing this element to try to make the number on both sides equal. You may need to do this to more than one substance. Never change the formula. Repeat steps 3 and 4 for the other elements in the formulae until there are equal numbers of each one on both sides. This is the balanced equation.
Add the state symbols if required.
Example sodium + water → sodium hydroxide + hydrogen
2Na
+ H2O → 2
NaOH
+
H2
Hydrogen: there are two H atoms on the left but three on the right. The equation is not balanced.
Add a 2 in front of H2O … 2Na + 2H2O → 2 NaOH + H2 There are now 2 × 2 = 4 H atoms on the left. So add a 2 in front of NaOH on the right to make the total on that side the same … 2Na
+ 2H2O →
2NaOH
+
H2
Sodium: there is one Na atom on the left but two on the right. Add a 2 in front of Na on the left … 2Na + 2H2O → 2NaOH + H2
2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)
© Pearson Education 2010. Edexcel GCSE Science Activity Pack. This document may have been altered from the original.
C1.8e A solid mass Sodium hydroxide dissolves in water to form a colourless solution. Copper sulfate dissolves in water to form a blue solution. When these two solutions are mixed together, a precipitation reaction occurs, producing a pale blue precipitate of copper hydroxide: sodium hydroxide + copper sulfate → sodium sulfate + copper hydroxide 2NaOH(aq) + CuSO4(aq) → Na2SO4(aq) + Cu(OH)2(s) You are going to investigate what happens to the total mass of the substances during this precipitation reaction.
Prediction 1
Will the total mass increase, decrease or stay the same during the reaction? Give reasons for your answer.
Apparatus eye protection plastic teat pipette cotton thread ignition tube scissors access to digital balance sodium hydroxide solution 250 cm3 conical flask with bung copper sulfate solution 25 cm3 measuring cylinder
Health and safety ●
Wear eye protection
●
Sodium hydroxide solution is corrosive. If splashed into the eyes, flood the eye with gently running tap water until a first aider arrives.
●
Copper sulfate solution is irritating to eyes and skin.
Method
A Use the measuring cylinder to add 25 cm3 of copper sulfate solution to the conical flask. B Tie some cotton thread just under the rim of the ignition tube. Leave several centimetres free. C Use the teat pipette to add sodium hydroxide solution to the ignition tube. Do not fill it more than halfway. D Carefully lower the ignition tube into the conical flask using the cotton thread. Allow the bottom of the ignition tube to touch the bottom of the flask, but take care not to mix the two liquids. E Stopper the flask so that the thread is held in place by the bung. F
Measure and record the mass of the whole apparatus.
G Carefully swirl the flask so that the two liquids mix inside it. Do not remove the bung. H Observe and record any changes in appearance of the reaction mixture. Measure and record the mass of the whole apparatus again.
Recording your results 2
Draw a suitable table for your results. It should include space to record the appearance of the reaction mixture and the two masses.
Considering your results/conclusions 3
Calculate the difference between the initial mass and the final mass.
4
Look at your answer to question 3. What do you notice?
5
Compare your results with your predictions. Were your predictions supported by the results? Do the results support the idea that no atoms are created or destroyed in a chemical reaction?
Evaluation 6
Compare your results with the results obtained by other students in the class. Describe any differences seen, and suggest reasons for these differences.
© Pearson Education 2010. Edexcel GCSE Science Activity Pack. This document may have been altered from the original.
C1.8f Balanced equations Name
Class
Date
Background ideas 1
What is the name of the smallest part of an element that can take part in a reaction?
2
What happens to the atoms in the reactants in a chemical reaction?
3
What happens to the total number of atoms of each element before and after a chemical reaction?
4
For each of the following chemical formulae, explain what each letter and number means.
5
a
CO2
b
CaCO3
c
Ca(OH)2 [Hint: there are two atoms of each element inside the brackets]
What do the state symbols (s), (l), (g) and (aq) mean?
Reactants and products Here is an unbalanced equation to show the reaction between lead nitrate and potassium iodide: Pb(NO3)2 + KI → PbI2 + KNO3 6
Identify the reactants and the products.
7
Explain why the equation is not balanced.
Balancing equations 8
Explain why the following equation is balanced: CaCO3 → CaO + CO2
9
Complete these equations (the lines indicate that a single substance is needed): a
CuCO3 → CuO + ______
b
______ → ZnO + CO2
10 Balance these equations (the dots indicate that a number is needed): a
…Ca + O2 → …CaO
b
CaCO3 + …HCl → CaCl2 + H2O + CO2
Extra challenge 11 Balance this equation: …Al + …O2 → …Al2O3
© Pearson Education 2010. Edexcel GCSE Science Activity Pack. This document may have been altered from the original.