Acid is a form of chemical, that dissociates to give hydrogen ions in aqueous solution. There are some chemical reactions related to acid that students need to know, and hence apply them. Note should be taken that these equations are very important for the topic, salt, which involves the preparation of salts.
Acids react with metals to produce salt and hydrogen gas.
- Take note that the metal need to be reactive. However, metals that are too reactive (like potassium) will reactive violently with acid. For metals that are not reactive, a reaction will not occur.
- For a reaction of lead with either hydrochloric acid & sulfuric acid, the liberation of hydrogen gas is initially observed. However, the liberation of hydrogen gas will then stop, due to the formation of lead(II) chloride and lead(II) sulfate, which are insoluble salts that ‘shield’ the lead metal from further reaction.
Acids react with oxides & hydroxides to produce water and salt.
- This reaction is also known as a neutralisation reaction.
- This reaction, especially the one between acid and hydroxide, is commonly observed in titration (volumetric analysis).
Acids react with carbonate to produce carbon dioxide, salt and water.
- The production of carbon dioxide and water can be linked to the thermal decomposition of metal carbonates.
The topic Acids and Bases is quite commonly tested in Singapore-Cambridge GCE ‘O’ Level Examinations, with specific association with the following topics:
- Qualitative Analysis (also known as volumetric analysis)
- Chemical Bonding