9.03.2 Neutralisation and making Salts
Syllabus
Acids are neutralised by alkalis (eg soluble Metal Hydroxides) and bases (eg insoluble Metal Hydroxides and Metal Oxides) to produce salts and water, and by Metal Carbonates to produce salts, water and Carbon Dioxide.
The particular salt produced in any reaction between an acid and a base or alkali depends on:
the acid used (Hydrochloric acid produces Chlorides, Nitric acid produces Nitrates, Sulphuric acid produces Sulphates)
the positive ions in the base, alkali or Carbonate.
Students should be able to:
predict products from given reactants
use the formulae of common ions to deduce the formulae of salts
What does this mean?
The neutralisation equation
You should learn the following general equation that shows what happens during neutralisation:
Acid + Alkali (Base) --> Salt + Water
A base is a substance that neutralises an acid. When they dissolve we call them alkalis.
Generally, at GCSE a base will be a Metal Oxide - Copper Oxide, Calcium Oxide, Magnesium Oxide etc.
Or a Metal Carbonate- Copper Carbonate, Calcium Carbonate, Magnesium Carbonateetc.
Many bases dissolve to form alkalis - Metal Hydroxides - Calcium Hydroxide, Magnesium Hydroxide etc.
But Copper Oxide is insoluble - it won't dissolve.
It can still neutralise an acid to make a salt but can't form an alkali .
Water is also made in neutralisation because
H+ (from acid) + OH-(from alkali) --> H2O
Naming Salts
The name of the salt you make depends on the name of the acid and the name of the alkali/base.
Bases/Alkalis start with the names of metals (or Ammonium) - so do salts.
So Sodium Hydroxide can only form Sodium salts, Calcium Oxide can only form Calcium salts etc.
The end of the salt depends on the name of the acid.
Sulfate is the textbook spelling now. But this is American and so deeply, deeply wrong on many levels. You can spell it either way, though Sulphate is the correct British spelling
So, because Acid + Alkali (Base) --> Salt + Water
Hydrochloric Acid + Sodium Oxide --> Sodium Chloride + Water
Sulphuric Acid + Calcium Hydroxide --> Calcium Sulphate + Water
Nitric Acid + Lithium Hydroxide --> Lithium Nitrate + Water
Acids and Metal Carbonates.
Metal Carbonates are also a type of base.
So they still react with acids to produce a salt + water but also release Carbon Dioxide gas that could be tested with Limewater.
Carbonate + Acid --> Salt + Water + Carbon Dioxide
The rules for naming salts are the same.
So,
Hydrochloric Acid + Sodium Carbonate --> Sodium Chloride + Water + Carbon Dioxide
Sulphuric Acid + Calcium Carbonate --> Calcium Sulphate + Water + Carbon Dioxide
Nitric Acid + Lithium Carbonate --> Lithium Nitrate + Water + Carbon Dioxide
Video
Past Paper Questions
