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JAMB Chemistry 2016 Paper

Question : 28

Total: 50

What volume of 0.5M H2SO4 will exactly neutralize 20cm3 of 0.1M NaOH Solution?

Solution:

Concept:

Neutralization uses the mole ratio from the balanced chemical equation.

Explanation:

Write the balanced equation:

\mathrm{H}_{2}\mathrm{SO}_{4} + 2\mathrm{NaOH} \to \mathrm{Na}_{2}\mathrm{SO}_{4} + 2\mathrm{H}_{2}\mathrm{O}

Moles of

\mathrm{NaOH}

present:

0.1\,\mathrm{M} \times 20\,\mathrm{cm}^{3} = 2\,\mathrm{mmol}

The equation shows that

1\,\mathrm{mol}

\mathrm{H}_{2}\mathrm{SO}_{4}

reacts with

2\,\mathrm{mol}

\mathrm{NaOH}

Thus, moles of

\mathrm{H}_{2}\mathrm{SO}_{4}

required:

\frac{2\,\mathrm{mmol}}{2} = 1\,\mathrm{mmol}

Volume of

0.5\,\mathrm{M}

\mathrm{H}_{2}\mathrm{SO}_{4}

needed:

V = \frac{n}{M} = \frac{1\,\mathrm{mmol}}{0.5\,\mathrm{M}} = 2.0\,\mathrm{cm}^{3}

So the correct option is A.

Answer:

2.0\,\mathrm{cm}^{3}

(Option A).

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