Neutralisation of Acids (GCSE Chemistry)
Neutralisation of Acids
Acid Neutralisation and Salt Production
Acid and Base Characteristics
- Acids have a low pH. Acids tend to have a pH of less than 7. When they are placed into aqueous solution, acids will ionise. Strong acids will ionise completely, whilst weak acids only ionise partially.
- Bases have a high pH. Bases tend to have a pH of more than 7. When they are placed in aqueous solution, bases are called alkalis. Alkalis will form hydroxide ions (OH-).
- Metal oxides and insoluble metal hydroxides are known as bases. As mentioned previously, alkalis are simply soluble metal hydroxides, that can dissolve in water.
Neutralisation Reactions
- Acids can react with bases. When an acid reacts with a base, this forms a salt and water. This reaction is known as neutralisation.
- Salt formation can occur. One of the products of a neutralisation reaction is a salt. This compound is formed from the acid and the metal (or positive ion) in the base.
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Salt Production
Three General Reactions
In this section, we’ll outline 3 general reactions between acids and bases. You’ll need to learn these for exams.
1.Metal Oxide + Acid → Salt + Water
E.g. MgO + 2HCl → MgCl2 + H2O
Magnesium oxide + hydrochloric acid → magnesium chloride + water
2. Metal Hydroxide + Acid → Salt + Water
2NaOH + H2SO4 → Na2SO4 + 2H2O
Sodium hydroxide + sulfuric acid → sodium sulfate + water
3. Metal carbonate + acid → salt + water + carbon dioxide
CaCO3 + 2HNO3 → Ca(NO3)2 + CO2 + H2O
Calcium carbonate + nitric acid → calcium nitrate + carbon dioxide + water
Predicting Salt Formation
As you can see from these three examples, we can predict the salt formed when given the reactants in an equation. There are three simple rules to remember:
- If we use hydrochloric acid, we will produce a chloride.
- If we use nitric acid, we will produce nitrates.
- If we use sulfuric acid, we will produce sulfates.
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