Chemistry 9701 · AS & A Level · Equilibria

Equilibria — practice question

When an aqueous solution of compound $G$, $\text{NH}_2\text{CH}_2\text{CH}_2\text{CH}_2\text{NH}_2$, is titrated using $\text{HCl(aq)}$, two acid-base reactions occur one after the other.
(a)[2]

Write the equations for these two acid-base reactions.

(b)[2]

The pH of a $0.10\,\text{mol dm}^{-3}$ solution of $G$ is $11.3$. After $30\,\text{cm}^3$ of $0.10\,\text{mol dm}^{-3}$ $\text{HCl}$ has been added to $10\,\text{cm}^3$ of a $0.10\,\text{mol dm}^{-3}$ solution of $G$, the final pH becomes $1.6$. On the axes below, sketch the pH variation during this addition of $\text{HCl(aq)}$.

Worked solution & mark scheme

This 4-mark question has a full step-by-step worked solution and mark scheme. One marking point: Equation for the first protonation step

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