An industrial chemist studying bleaching and sterilizing...

An industrial chemist studying bleaching and sterilizing prepares several hypochlorite buffers. Find the $\mathrm{pH}$ of (a) $0.100 M \mathrm{HClO}$ and $0.100 \mathrm{M} \mathrm{NaClO}$ (b) $0.100 M \mathrm{HClO}$ and $0.150 \mathrm{M} \mathrm{NaClO}$ (c) $0.150 M \mathrm{HClO}$ and $0.100 \mathrm{M} \mathrm{NaClO}$ (d) $1.0 \mathrm{~L}$ of the solution in part (a) after $0.0050 \mathrm{~mol}$ of $\mathrm{NaOH}$ has been added

An industrial chemist studying bleaching and sterilizing prepares several hypochlorite buffers. Find the $\mathrm{pH}$ of
(a) $0.100 M \mathrm{HClO}$ and $0.100 \mathrm{M} \mathrm{NaClO}$
(b) $0.100 M \mathrm{HClO}$ and $0.150 \mathrm{M} \mathrm{NaClO}$
(c) $0.150 M \mathrm{HClO}$ and $0.100 \mathrm{M} \mathrm{NaClO}$
(d) $1.0 \mathrm{~L}$ of the solution in part (a) after $0.0050 \mathrm{~mol}$ of $\mathrm{NaOH}$ has been added

Key Concepts

Weak Acid and Conjugate Base Equilibrium

In buffer solutions, the weak acid partially dissociates into its conjugate base and hydrogen ions. The equilibrium established between the weak acid and its conjugate base is characterized by the acid dissociation constant (Ka), which indicates the extent of acid dissociation. Understanding this equilibrium is crucial in predicting how changes in the concentrations of the components affect the pH.

Effect of Titration on Buffer pH

When a strong base or acid is added to a buffer solution, it reacts with one of the buffer components, altering their ratio. This leads to a change in the pH of the solution that can be calculated by adjusting the amounts of the weak acid and its conjugate base, typically using the Henderson-Hasselbalch equation. This concept is key in understanding buffer capacity and the limits of a buffer's ability to maintain pH.

Buffer Solutions

A buffer solution is composed of a weak acid and its conjugate base (or a weak base and its conjugate acid) in comparable amounts. Such solutions resist changes in pH when small quantities of acid or base are added, making them essential in many chemical and biological processes where maintaining pH is critical.

Henderson-Hasselbalch Equation

The Henderson-Hasselbalch equation is a mathematical relation used to estimate the pH of a buffer solution. It relates the pH to the pKa of the weak acid and the ratio of the concentrations of the conjugate base and the acid. This equation simplifies pH calculations in buffer systems for both preparation and analysis purposes.

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