Acids and alkalis

Июль 30, 2022

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Acids and alkalis

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2. Acids and alkalis Solutions can be sorted by whether they are: acid, alkali or neutral. When
3. When the oxide of some non-metals dissolve in water they make an acid. Acids have a
4. Acids react with metals and carbonates. Metal + Acid Salt + Hydrogen magnesium + magnesium chloride
5. Acids Lemon juice contains citric acid, and vinegar contains ethanoic acid. Some strong acids are hydrochloric
6. Neutralisation Acids and alkalis react with each other. The alkali cancels out the acid in the
7. Salts The salt made depends on the acid and alkali used. The salt contains the metal
8. Alkalis When the oxides of some metals dissolve in water they make an alkali solution. Alkalis
9. Alkalis Alkalis are present in many cleaning substances in use in our homes. Kitchen cleaners are
10. Indicators They change colour in acid or alkaline solutions. Different indicators change to different colours. Indicators
11. Litmus Test Litmus is an indicator. It changes colour in acid and alkaline solutions. Litmus is
12. Universal Indicator Universal indicator changes colour in acids and alkalis. Its colour shows the strength of
13. The pH scale 1 – 6 8 - 14 Alkalis 7 Neutral Acids
14. Applications of Neutralisation Indigestion: Our stomach carries around hydrochloric acid. Too much of this leads to
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Acids and alkalis
Solutions can be sorted by whether they are:

acid, alkali or neutral.

When a substance dissolves in water it makes a solution.

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When the oxide
of some non-metals
dissolve in water
they make

an acid.
Acids have a sour taste.
They are corrosive.

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Acids react with metals and carbonates.
Metal + Acid Salt + Hydrogen
magnesium

+ magnesium chloride + hydrochloric acid hydrogen

Acid + Carbonate Salt + Water + Carbon
dioxide
sulphuric acid + copper sulphate + water +
copper carbonate carbon dioxide

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Acids
Lemon juice contains citric acid, and vinegar contains ethanoic acid.
Some

strong acids are hydrochloric acid, sulphuric acid and nitric acid.
Some weak acids are ethanoic acid, citric acid and carbonic acid.

There are many acids present in our everyday lives.

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Neutralisation
Acids and alkalis react with each other. The alkali cancels out

the acid in the reaction. This is called neutralisation.

A salt is made.

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Salts
The salt made depends on the acid and alkali used.
The

salt contains the metal atom from the alkali, and part of the acid molecule.

The salts of sulphuric acid are known as sulphates.
The salts of hydrochloric acid are known as chlorides.
The salts of nitric acid are known as nitrates.

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Alkalis
When the oxides of some metals dissolve in water they

make an alkali solution.
Alkalis react with acids and neutralise them.

Many everyday substances are alkalis.
They feel soapy.
They are corrosive.

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Alkalis
Alkalis are present in many cleaning substances in use in

our homes.
Kitchen cleaners are alkaline because they contain ammonia or sodium hydroxide, which attack grease.

Calcium hydroxide and sodium hydroxide are strong alkalis.
The most recognisable and common weak alkali is ammonia.

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Indicators
They change colour in acid or alkaline solutions.
Different indicators change

to different colours.

Indicators help you find out whether a solution is acidic or not.

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Litmus Test
Litmus is an indicator. It changes colour in acid and alkaline

solutions.
Litmus is red in an acid.
Litmus is blue in an alkali.

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Universal Indicator
Universal indicator changes colour in acids and alkalis.
Its colour

shows the strength of an acid or alkali.

ACIDS

ALKALIS

Neutral

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The pH scale
1 – 6
8 - 14
Alkalis
7
Neutral
Acids

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Applications of Neutralisation
Indigestion: Our stomach carries
around hydrochloric acid.

Too much of this leads to indigestion.
To cure indigestion, you can neutralise the excess acid with baking soda or specialised indigestion tablets.

Insect Stings
Bee stings are acidic
and can be neutralised with
baking soda (bicarbonate of soda).
Wasp stings are alkaline and can be neutralised with vinegar.