Question

Ammonium sulphate is an example of:
[A] An acid
[B] A base
[C] An acidic salt
[D] A basic salt

Answer 1

Hint: We get ammonium sulphate on neutralisation of sulphuric acid with ammonium hydroxide. Neutralisation of a strong acid with a weak base gives us a salt which upon dissolving in a solvent makes the solution acidic.

Complete step by step answer:
 To answer this question, let us discuss what an acid, base and their respective salts are.
Firstly, we have acid which we know is a proton donor species. It can donate its proton, hydrogen ions or accept electrons. Acids are strong oxidising agents.
Then we have base. We know that a base is a proton acceptor species and it accepts protons and hydrogen ions or can donate electrons. Bases are strong reducing agents.
There are many theories which describe acids and bases in different ways but generally we can describe them as above.
Next we have an acidic salt. We know that in chemistry, salt is a chemical compound which contains cation and anions in specific proportions so that it is electrically neutral. An acid salt is a salt which will produce an acidic solution after being dissolved in a solvent. We can form then neutralizing strong acids with a weak base.
And lastly, we have basic salt. It is a salt which upon dissolving in a solution will form a basic solution. We can form basic salts by neutralising strong bases with a weak acid.
In the question, ammonium sulphate is given to us which is ${{\left( N{{H}_{4}} \right)}_{2}}S{{O}_{4}}$ . It is a salt of a weak base and a strong acid. Ammonium sulphate is formed by the neutralisation of sulphuric acid which is a strong acid by ammonium hydroxide which is a weak base. We know acid and base gives us a salt and water, therefore we can write the reaction as-

     \[{{H}_{2}}S{{O}_{4}}(S.A)+N{{H}_{4}}OH(W.B)\to {{\left( N{{H}_{4}} \right)}_{2}}S{{O}_{4}}+{{H}_{2}}O\]
Ammonium sulphate is a salt from a strong acid and a weak base thus is an acidic salt.
So, the correct answer is “Option C”.

Note: We have discussed above about the reactions between strong acid with a weak base and weak base with a strong acid but a neutralisation reaction between a strong acid and a strong base gives us a salt with a neutral pH. For example sodium chloride which is formed by the neutralisation of hydrochloric acid by sodium hydroxide. Sodium chloride in water shows neither acidic nor basic properties.
                      \[NaOH+HCl\to NaCl+{{H}_{2}}O\]