JAMB Chemistry 2018 Paper

Concept:Sulfuric acid is a strong diprotic acid, so its hydrogen ion concentration is twice the acid concentration.Explanation:The dissociation of sulfuric acid in water is represented by the equation:$$\mathrm{H_2SO_4(aq) \rightarrow 2H^+(aq) + SO_4^{2-}(aq)}$$The balanced equation shows that one molecule of $\mathrm{H_2SO_4}$ produces two hydrogen ions.Therefore, the concentration of hydrogen ions is:$$[\mathrm{H^+}] = 2 \times 0.05\ \mathrm{mol\,dm^{-3}} = 0.10\ \mathrm{mol\,dm^{-3}}$$pH is defined using the formula:$$\mathrm{pH} = -\log_{10}[\mathrm{H^+}]$$Substitute the hydrogen ion concentration into the formula:$$\mathrm{pH} = -\log_{10}(0.10)$$Since $-\log_{10}(0.10) = 1.00$, the pH of the solution is $1.00$.Answer:C. $1.00$