C1.10a How much acid? Name
Class
Date
You are going to find out how much hydrochloric acid it takes to neutralise a given amount of sodium hydroxide solution (an alkali). The method you will use is called a titration. You do not need to remember how to do a titration.
Apparatus eye protection
burette
conical flask
clamp and stand
measuring cylinder
small beaker
small funnel
white tile or white paper
hydrochloric acid IRRITANT
methyl orange indicator
sodium hydroxide solution IRRITANT
Health and safety ●
Wear eye protection
●
Hydrochloric acid and sodium hydroxide are IRRITANT. Wash off any spills on skin or clothing with plenty of water.
Method A Set up the apparatus as shown in the diagram. Make sure the tap at the bottom of the burette is closed. Adjust the height of the burette so that the tip will be just above the top of the conical flask. Remove the flask. B Use the funnel to help you to pour some hydrochloric acid into the burette. Put the beaker under the burette and open the tap to let some acid into the tip of the burette. Close the tap again and pour the acid burette in the beaker down the sink. C Fill the burette up to just below the zero mark with hydrochloric acid – this does not have to be exact. D Use the measuring cylinder to pour exactly 10 cm3 sodium hydroxide solution into to the conical flask. Add a few drops of methyl orange indicator and swirl it so that the liquids mix. Stand the flask under the burette.
clamp and stand
E Read the volume of acid in the burette and write it down. F
Add the acid from the burette to the flask a little at a time – about 1 cm3 each time is about right. Swirl the flask gently each time you add some acid. Stop when the indicator turns red and stays red.
conical flask
G Record the volume of acid in the burette. Work out how much acid has been added and write it down. H Wash out the conical flask with deionised water and repeat steps D to G. This time, add acid about 1 cm3 at a time until you have nearly added the same amount as before. Then add acid in much smaller amounts – drop by drop.
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Sheet 1 of 2
C1.10a How much acid? (cont.) Recording your results 1
Draw a table to record the initial and final readings on the burette and the calculated volume of acid added.
Considering your results/conclusions 2
What volume of acid did it take to neutralise the alkali?
Evaluation 3
Suggest why you did the titration twice. ___________________________________________________________________________ ___________________________________________________________________________
4
What was the purpose of the white tile?
5
How do your results compare with the results of others? ___________________________________________________________________________ ___________________________________________________________________________
6
How could you make your titration more accurate? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________
Š Pearson Education 2010. Edexcel GCSE Science Activity Pack This document may have been altered from the original.
Sheet 2 of 2
C1.10b Formulae and equations 1
2
Cut out the cards, and match the names of the compounds to their formulae.
aluminium chloride
aluminium hydroxide
calcium carbonate
calcium chloride
carbon dioxide
hydrochloric acid
magnesium carbonate
magnesium chloride
magnesium hydroxide
water
CaCO3
MgCO3
HCl
Mg(OH)2
Al(OH)3
CO2
H2O
CaCl2
MgCl2
AlCl3
Use the cards to help you to complete the following word equations: a
hydrochloric acid + magnesium hydroxide →
b
hydrochloric acid + calcium carbonate →
c
hydrochloric acid + aluminium hydroxide →
© Pearson Education 2010. Edexcel GCSE Science Activity Pack This document may have been altered from the original.
C1.10c Acids and indigestion Name 1
Class
Date
Why does your stomach produce acid? Tick two boxes. to neutralise alkalis in your food
to kill bacteria
to allow digestive enzymes to work properly
to make food taste nicer
2 A
A B
H
3
4
I
a
What H is the acid found in your stomach? _______________________________
b
What A is a cure for indigestion? _______________________________________
c
What B can neutralise an acid? ________________________________________
d
What A is a base that will dissolve in water? ______________________________
e
What I can show whether a liquid is an acid? _____________________________
Which of these substances might be the effective ingredient in an indigestion remedy? There is more than one answer. acid
magnesium hydroxide
calcium carbonate
calcium chloride
magnesium chloride
water
These word equations show what happens when an indigestion remedy enters your stomach. Fill in the gaps. a acid b
c
+ calcium → calcium + water + carbon carbonate chloride dioxide
hydrochloric + magnesium → acid carbonate hydrochloric + magnesium → magnesium acid hydroxide
© Pearson Education 2010. Edexcel GCSE Science Activity Pack This document may have been altered from the original.
+ water + carbon dioxide +
C1.10d Natural remedies These are extracts from websites and magazines recommending 'natural' remedies for indigestion.
a into l of baking sod fu n o o sp e rg la Mix 1 away. Drink straight
f water.
a small glass o
Squeeze the ju ice from a lem on into a glass Stir and drink of warm water it in one go. .
le juice after every meal Drink a glass of pineapp
to prevent indigestion. r some range o
grapes.
Eat an o
Swallow a table spoon of white wine vinegar o you feel indiges r cider vinegar tion pains starti as soon as ng. ach. ur stom o y o t n a oil o and soy l i o c i l f gar ixture o m a b u R water'. eet that 'makes your mouth sw er oth y an or , int erm Suck on a pepp
1
What causes indigestion?
2
How do commercial indigestion remedies work?
3
a
Name one substance often found in indigestion remedies and give its chemical formula.
b
Write a balanced equation to show what happens when this substance reacts with stomach acid.
4
Which of the 'natural' remedies above would work in a similar way to the above remedy? Explain your answer.
5
Which of the natural remedies might make indigestion worse? Explain your answer.
6
Which remedy do you think is not likely to make any difference? Explain your answer.
7
Suggest why sucking a sweet might help to relieve indigestion.
Extra challenge 8
How could you test the various natural remedies to find out how well they work?
Š Pearson Education 2010. Edexcel GCSE Science Activity Pack This document may have been altered from the original.