1. Look Think Discuss Agree Share Write
KEYWORDS
PROCESSES
CONCEPTS
What is today's lesson about?
Write in front of your book

2. what are common examples of neutralisation?
Sunday, 23 April 2017
Learning Intention
Neutralisation
what are common examples of neutralisation?
Learning objectives
All
(must)
explain how acids and alkali’s can be used in a neutralisation reaction
Recall the pH of acids alkalis and neutral substances
describe pH changes on neutralisation or dilution of an acid or an alkali;
Most
(Should)
Explain how indigestion tablets overcome extra stomach acid
describe some applications of neutralisation reactions;
Some
(could)
Investigate different indigestion products in a neutralisation reaction

3. Look Think Discuss Agree Share Write
1 Are these things acid or alkali?
vinegar
toothpaste
orange juice
indigestion tablets
2 True or false?
When an acid and an alkali react it is called combustion.
Adding an acid to an alkali makes the pH number go up.
When you add an acid to an alkali it can make the solution neutral.
Indigestion is caused by having too much acid in the stomach.
3 Draw lines to match the words to the correct explanations.
Making an acid weaker by mixing it with water is …
universal indicator
A chemical that can get rid of an acid is an …
diluting
A chemical that can change colour to show the pH is
pickling
antacid
Keeping food from going bad by putting in an acid like vinegar is …

4. Neutralisation – Hydrochloric acid

5. Neutralisation – Sulphuric acid

6. Put in 3 ml of water
Add 1 spatula full of indigestion tablet,
mix them together, until all powder dissolves if some remains undissolved, add more water
In separate test tube add 5ml of acid
Add UI solution
Add dissolved indigestion tablet into acid 0.5ml at a time, record how much you use to turn UI green

7. Neutralisation – Nitric acid

8. Neutralisation - Indigestion
If we have too much acid in our stomachs, we get indigestion.
Acid can move up out of our stomach creating a burning feeling in the chest.
We neutralise the excess acid by taking a tablet containing a base.
This is usually a carbonate or an oxide.
Strong soluble bases (like sodium hydroxide) would create too alkaline a solution and cannot be used.
Alkali
Acid 1 2 14 13 12 11 10 9 8 7 6 5 4 3

9. Neutralisation - Stings
A bee sting is acidic.
A wasp sting is alkaline.
So one way to treat a an acidic bee sting is to dab on a base: bicarbonate of soda more properly known as sodium hydrogen carbonate.
One way to treat a basic wasp’s sting is with an acid : vinegar - ethanoic acid.

10. Pay attention to the animation at the end You are going to play “ find the fiction”
So you will need 3 or 4 facts about Neutralisation reactions
Write 3 or four “facts/statements” about neutralisation ONE must be incorrect the others should be correct

11. Apparatus Wear eye protection.
• test tube rack containing 4 test tubes and Sodium carbonate is an
1 boiling tube, with chemicals in them irritant.
• eye protection
In this activity you will be using your senses to make observations.
You will also need to follow instructions carefully.
If you are careful, you should be able to produce a rainbow effect in the tube.
Method
A The boiling tube contains sodium carbonate. Describe the appearance of the substance in the tube.
B Test tube 1 contains water. Add the water to the boiling tube. Feel the outside of the tube.
Describe what you see and what you can feel.
C Shake the tube. Describe what you can see now.
D Tube 2 contains universal indicator. Smell the tube carefully by wafting the smell towards you. Describe the appearance and the smell of the liquid in the tube.
E Add the universal indicator to the boiling tube. Observe the tube without shaking. What do you see?
F Now shake the tube. What do you see now? What type of substance is sodium carbonate?
G Tubes 3 and 4 contain ethanoic acid. Smell each tube carefully by wafting the smell towards you. Describe the appearance and the smell of the liquid in the tubes.
H Add the contents of tube 3 to the boiling tube. Do not shake the tube. Describe what happens.
I Very carefully pour the contents of tube 4 into the boiling tube. You may find it helpful to tilt the boiling tube slightly as shown in the diagram.
Do not shake the tube. Describe what you see.
J Explain why you get the ‘rainbow’ effect.

12. A The substance in the boiling tube was a .
When I added the water to the boiling tube I saw and the tube felt .
When I shook the tube .
The smell of the universal indicator in tube 2 was .
The colour of the liquid in tube 2 was .
Was the liquid in tube 2 clear or cloudy?
When I added the universal indicator to the boiling tube the colour went .
When I shook the tube .
Is sodium carbonate acid, alkali or neutral?
The smell in tubes 3 and 4 reminded me of .
When I added the liquid in tube 3 to the boiling tube .
When I added the liquid in tube 4 to the boiling tube I saw different colours.
These were: .
I also saw .
The liquid in the tube was more acidic in the part of the tube and more at the bottom. In the middle of the tube the mixture is . This is where the and the alkali cancel each other out.

13. Which indigestion remedy works best?
Indigestion remedies react with acid in our stomachs and cancel it out. We can test different indigestion remedies by reacting them with some dilute acid and measuring the pH of the mixture after it stops reacting.
Planning
1 When you plan your experiment you should think about these things:
Apparatus
• various indigestion remedies
• stop clock
• dilute hydrochloric acid
• 250 cm3 beaker
• universal indicator paper or solution
• eye protection
• electronic balance
The remedies should not be tasted.
What apparatus will you use?
How many different indigestion remedies will you use?
Which factor(s) will you keep the same in each test?
What will you measure each time?
How will this tell you which is the best indigestion remedy?
Will you add the solid to the acid, or the acid to the solid?
How much of the indigestion remedy will you use?
How much acid will you use?
How will you test the pH?
When will you test the pH – before adding the remedy, after adding it, or both before and after?
What will you do to make sure that this is a fair test?
What will you do to make sure that it is an accurate test?
Safety and risk assessments
2 What do you need to do to make sure you are safe?
• What are the possible dangers in this experiment?
• How can you control the risks?
Get your teacher to check your plan before starting the experiment.

14. Recording your results
5 Design a results table to record your results.
Considering your results/conclusions
6 a What happened to the pH when the remedies reacted with the acid?
b Was this what you predicted?
7 a Which remedy worked best?
b How do you know?
Evaluation
8 Can you suggest improvements to the way the experiment was done, to make the results more precise?

15. Which plan works best?
Indigestion remedies react with acid in our stomachs and cancel it out. We can test different indigestion remedies by reacting them with some dilute acid. Several students worked out a plan
for doing their experiments, and each one used a different method. They were all told to crush
up the tablets into powder before they started. There were four different brands of indigestion remedies to try.
Cherie’s plan
I’m going to keep it a fair test by using the same amount of acid and indigestion remedy for each test. You’ve got to keep everything the same to make it fair. I’ll put the indigestion remedy in the tubes with the acid and see if it fizzes up and that way I’ll know if it’s gone neutral and so I’ll be able to tell if it’s the best.
Amy’s plan
I’m going to put the same amount of acid in each beaker (20 cm3). I’m then going to take a spatula of powder at a time and add it to the acid. I’ll test the liquid with universal indicator paper. I’m going to keep going until it changes to pH 7 and I’m going to count the number of spatulas of powder I need. I’ll do it again to make sure it was a fair test.
Byron’s plan
I’m going to fill up four tubes half full with acid and then add two spatulas of indigestion remedy to each one. I’ll measure the pH at the end of the experiment to see which remedy has been the best at neutralising the acid. ?
1 In all four plans, which was the factor that
was different in each test?
2 Which variable was measured by:
a Byron? b Dimitri?
3 What did Amy and Cherie both keep the same in their experiments?
4 Compare Amy’s plan with Dimitri’s.
a What do the two plans have in common?
b How is Dimitri’s plan different from Amy’s?
5 Cherie said that she kept everything the same to make it a fair test. Is she correct? Explain your answer.
6 a Which two people decided to repeat their tests?
b Who gave the best reason for doing the repeats? Why
7 Compare Amy’s method with Byron’s. Do you think one is likely to give better results or are they
both equally good? Explain your reasons.
Dimitri’s plan
I’m going to put two grams of the powder into a beaker and then I’m going to add some water to help it dissolve a bit. 20 cm3 of water should be enough. Then I’ll put some universal indicator in (and it should go blue or purple). I’m going to put the acid in a burette (I’m using this because it’s very accurate and you can get readings down to 0.1 cm3, which is better than a measuring cylinder). Then I’m going to add acid a little bit at a time and watch the colour of the indicator. As soon as it goes green I’ll stop and write down how much acid I’ve used (unless it goes orange or red, in which case I might take a bit off my reading because I’ll have gone too far). I’ll repeat all the tests again and take an average of the two results. This will make it more accurate.

16. How sherbet works
When two chemicals are mixed together, they sometimes make a new substance. Citric acid and bicarbonate of soda change when they are mixed with water.
When you put the sherbet mixture in your mouth, the moisture from your tongue helps the acid to react with the alkali. When this happens, carbon dioxide gas is given off. This makes the fizz on your tongue. The acid also gives the sherbet its tangy flavour.
The word equation for this reaction is:
sugar (icing sugar is likely to be best)
citric acid (the acid in oranges, lemons and grapefruit)
bicarbonate of soda.
citric acid + sodium hydrogencarbonate  carbon dioxide + sodium citrate + water
1 Which of the ingredients in sherbet is:
a an acid b an alkali c neutral?
2 Which ingredient makes the sherbet taste:
a sweet
b tangy?
3 Which two ingredients are needed to make the sherbet fizzy?
4 What is the name of the ‘fizz gas’ in sherbet?
5 What is the proper chemical name for bicarbonate of soda?
6 If you get the recipe for sherbet wrong, how might it affect the taste?
7 Plan an investigation to find the best recipe for sherbet. Write brief notes only.
8 Suggest a mixture of the ingredients that you think might give a tangy taste and a good fizz.

17. Neutralisation – Soil pH
Plants remove compounds from the soil in a way that tends to leave the soil acidic.
Many plants won’t grow well in acid soil and so farmers have to regularly check the pH and adjust it by adding a base.
Calcium carbonate or calcium hydroxide are cheap and so are often used for this purpose.

18. Neutralisation – Soil fertilisers
Plants also remove nitrogen compounds from the soil and this is often replaced using fertiliser.
Ammonia is a water soluble gas high in nitrogen and in some countries it is injected directly into moist soil. However, because it is a gas much of it is quickly lost.
In the UK ammonia is dissolved in water to give ammonium hydroxide (an alkali) and this is neutralised by reacting it with nitric acid to give a solid nitrogen rich fertiliser. 
nitric acid +
ammonium hydroxide
ammonium nitrate +
water
NH4OH +
HNO3 
NH4NO3
H2O

19. Neutralisation - acid gases
Many power stations burn coal containing sulphur.
When this burns it produces acidic sulphur oxides which can cause acid rain.
The gases are “scrubbed”, as much as possible, of these acidic oxides by reacting them with a base before releasing them into the air.
Calcium oxide or calcium hydroxide are often used for this purpose.

20. YES
I have enjoyed the lesson and learnt a lot and completed my class activity.
SOME
I have understood some of the work and haven’t finished it all NO
I have found it difficult to learn today and I have done very little work

21. Science Department Marking your work
Strength
Say what you have done well
Target
This is something that you could do to improve your work and/or take the next step forward.
Effort
a comment about your overall effort here. Sometimes this will be a number.
1- Excellent 2 – Good effort 3 – Satisfactory More effort needed
Pupil comment
write your own pupil comment.
It should show how well you think that you have understood the work.