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Home > Chemistry > Acids > Reactions of acids

Chemistry

Reactions of acids

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In this Revision Bite you will revise some important information about the reactions of acids.

What happens in a neutralisation reaction (General)

Neutralisation is the reaction of acids with neutralisers eg. alkalis [alkali: A base which is soluble in water.

In a neutralisation reaction the pH of the acid moves up towards 7. If an alkali is being used as the neutraliser its pH moves down towards 7.

In this video, an acid with a pH of 4 and an alkali with a pH of 11 are used to neutralise each other. This forms a solution with a pH of 7.

Video clip: Neutral solutions

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An overly acidic stomach may require neutralisation as shown in this clip.

Video clip: Neutralising the stomach

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New substances called SALTS and water are formed in neutralisation reactions. The name of the salt that is produced depends on the type of acid and the type of neutraliser being used.

The reaction of hydrogen [hydrogen: diatomic gas that can be detected by a burning splint 'popping'. ions H+ (aq) to form water is an example of neutralisation.

Example question

Here is a typical Standard Grade question. Use the information above to help you answer it. Look at the answer after you have tried to do it.

Question

a) Explain what is meant by a neutralisation reaction.

b) What happens to the pH of an acid as it is neutralised?

c) What happens to the pH of an alkali as it is neutralised?

Answer

a) Neutralisation is the reaction of an acid with neutralisers such as alkalis, carbonates and metal oxides, which produces water and a salt.

b) The pH of an acid increases towards 7 in a neutralisation reaction.

c) The pH of an alkali decreases towards 7 in a neutralisation reaction.

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Watch

Flasks

Class Clips

Take a look at the effect of pH on food.

Watch

PH indicator

Class Clips

Why is it important to know why certain substances are acidic, neutral, or alkaline? Watch to find out.

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