Suggest three ways in which salts can be prepared in the laboratory and explain why ammonium chloride solution is acidic.

Here's the answer to the question:

a) Suggest three ways in which salts can be prepared in the laboratory.

• Neutralization: Reaction between an acid and a base (e.g., $\text{HCl} + \text{NaOH} \to \text{NaCl} + \text{H}_2\text{O}$).
• Reaction of an acid with a metal: For reactive metals (e.g., $\text{Mg} + \text{H}_2\text{SO}_4 \to \text{MgSO}_4 + \text{H}_2$).
• Precipitation: Mixing two soluble salt solutions to form an insoluble salt (e.g., $\text{AgNO}_3(aq) + \text{NaCl}(aq) \to \text{AgCl}(s) + \text{NaNO}_3(aq)$).

b) Explain why when ammonium chloride was dissolved in water and the solution tested, it was found to be acidic.
Ammonium chloride ($\text{NH}_4\text{Cl}$) is a salt formed from a strong acid ($\text{HCl}$) and a weak base ($\text{NH}_3$). When dissolved in water, the ammonium ion ($\text{NH}_4^+$) hydrolyzes, reacting with water to produce ammonia ($\text{NH}_3$) and hydronium ions ($\text{H}_3\text{O}^+$), which makes the solution acidic. The chloride ion ($\text{Cl}^-$) does not hydrolyze significantly.

$$\text{NH}_4^+(aq) + \text{H}_2\text{O}(l) \rightleftharpoons \text{NH}_3(aq) + \text{H}_3\text{O}^+(aq)$$

c) State three other applications of salts in your community.

• Food preservation and seasoning: Sodium chloride (table salt) is used to season food and preserve meat and fish.
• Fertilizers: Salts like ammonium nitrate and potassium chloride are used as fertilizers to enrich soil and promote plant growth.
• Building materials: Calcium carbonate (limestone) is a salt used in the production of cement and as a building material.