Which indicator would be the most appropriate for titrating aqueous ethylamine, ${\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{NH}}_2$ , with nitric acid, ${\mathrm{HNO}}_3$?

A $0.10 \mathrm{mol} {\mathrm{dm}}^{-3}$ ammonia solution is placed in a flask and titrated with a $0.10 \mathrm{mol} {\mathrm{dm}}^{-3}$ hydrochloric acid solution.

Explain why the pH of the ammonia solution is less than $13$.

A $0.10 \mathrm{mol} {\mathrm{dm}}^{-3}$ ammonia solution is placed in a flask and titrated with a $0.10 \mathrm{mol} {\mathrm{dm}}^{-3}$ hydrochloric acid solution.

When half the ammonia has been neutralized (the half-equivalence point), the pH of the solution is $9.25$. Deduce the relationship between $\left[{\mathrm{NH}}_3\right]$ and $\left[{\mathrm{NH}}_4^{+}\right]$ at the half equivalence point.

A $0.10 \mathrm{mol} {\mathrm{dm}}^{-3}$ ammonia solution is placed in a flask and titrated with a $0.10 \mathrm{mol} {\mathrm{dm}}^{-3}$ hydrochloric acid solution.

Determine ${\mathrm{pK}}_{\mathrm{b}}$ and ${\mathrm{K}}_{\mathrm{b}}$ for ammonia based on the pH at the half-equivalence point.

A $0.10 \mathrm{mol} {\mathrm{dm}}^{-3}$ ammonia solution is placed in a flask and titrated with a $0.10 \mathrm{mol} {\mathrm{dm}}^{-3}$ hydrochloric acid solution.

Describe the significance of the halfequivalence point in terms of its effectiveness as a buffer.

When these $1.0 \mathrm{mol} {\mathrm{dm}}^3$ acidic solutions are arranged in order of increasing strength (weakest first), what is the correct order?

Acid in solution X : ${\mathrm{K}}_{\mathrm{a}}=1.74\times {10}^{-5} \mathrm{mol} {\mathrm{dm}}^{-3} \mathrm{at} 298 \mathrm{K}$ 

Acid in solution Y : ${\mathrm{K}}_{\mathrm{a}}=1.38\times {10}^{-3} \mathrm{mol} {\mathrm{dm}}^{-3} \mathrm{at} 298 \mathrm{K}$ 

Acid in solution Z : ${\mathrm{K}}_{\mathrm{a}}=1.78\times {10}^{-5} \mathrm{mol} {\mathrm{dm}}^{-3} \mathrm{at} 298\mathrm{K}$

Consider an acid–base indicator solution.

$$\begin{gathered} \mathrm{HIn}\left(\mathrm{aq}\right) \rightleftharpoons {\mathrm{H}}^{+}\left(\mathrm{aq}\right)+{\mathrm{In}}^{-}\left(\mathrm{aq}\right) \\ \mathrm{colour} \mathrm{A} \mathrm{colour} \mathrm{B} \end{gathered}$$

What is the effect on this acid–base indicator when sodium hydroxide solution is added to it?