Write an expression for the $K_a$ of $\text{Cl(CH}_2)_3\text{CO}_2\text{H}(aq)$.
Write a mathematical expression showing how $K_a$ and $pK_a$ are related.
Calculate $[\text{H}^+]$ in solutions Y and Z.
Calculate the ratio $\dfrac{[\text{HCl}]\,\text{dissolved in solution Y}}{[\text{Cl(CH}_2)_3\text{CO}_2\text{H}]\,\text{dissolved in solution Z}$.
A buffer solution of pH $5.00$ is made by adding sodium propanoate to $5.00\,\text{g}$ of propanoic acid in $100\,\text{cm}^3$ of distilled water. Calculate the mass of sodium propanoate needed to make this buffer solution. The $K_a$ of propanoic acid is $1.35 \times 10^{-5}\,\text{mol dm}^{-3}$. $[M_r: \text{propanoic acid},\,74.0;\, \text{sodium propanoate},\,96.0]$.
Some dilute sulfuric acid is added to a small sample of the buffer solution described in (b). The final pH of the mixture is close to $1$. Explain this observation.