JAMB Chemistry 2024 Paper

Concept:In an acid-base titration, the volume of acid needed is found using the concentration-volume relation, provided the reacting mole ratio is known.Explanation:Write the balanced equation for the neutralisation reaction.$$\mathrm{HCl} + \mathrm{NaOH} \rightarrow \mathrm{NaCl} + \mathrm{H}_2\mathrm{O}$$The mole ratio of acid to base is $1:1$.This means the acid and base react in equal molar amounts.Given values are:Concentration of acid, $C_A = 0.12\ \mathrm{mol\,dm^{-3}}$Volume of acid, $V_A = ?$Concentration of base, $C_B = 0.20\ \mathrm{mol\,dm^{-3}}$Volume of base, $V_B = 20\ \mathrm{cm^3}$Apply the titration formula, $C_A V_A = C_B V_B$.Make $V_A$ the subject of the formula, giving $V_A = \frac{C_B V_B}{C_A}$.Substitute the values, $V_A = \frac{0.20 \times 20}{0.12}$.Calculate the result, $V_A = 33.33\ \mathrm{cm^3}$.Answer:The required volume is $33.33\ \mathrm{cm^3}$, which corresponds to Option C.