Acid–base Equilibria

Question

Which change increases the pH of an acetic acid/sodium acetate buffer the most?

RankGuru · Accepted Answer

1. **The Equation**: $pH = pK_a + \log \frac{[Acetate]}{[Acetic\ Acid]}$.
2. **Mechanics**: To increase $pH$, the value inside the log must increase.
3. **Analysis**:
   - **HCl**: Adds $H^+$, reacts with acetate to form acetic acid. Ratio decreases, $pH$ drops.
   - **Dilution**: Both concentrations drop equally. The ratio stays constant; $pH$ hardly changes (though buffer capacity drops).
   - **Sodium Acetate**: Directly increases the numerator $[Salt]$, increasing the ratio and thus the **$pH$ rises**.
   - **Acetic Acid**: Increases the denominator, $pH$ drops.
4. **Conclusion**: **Adding solid Sodium Acetate** is the most effective way to raise the $pH$.

Rank Guru

Acid–base Equilibria

Select the correct option:

Solution

🔒 Solution Hidden from View

More acid–base equilibria Practice Questions

The percent dissociation of a 1.0×10⁻³ M solution of a weak monoprotic acid (Ka = 1.0×10⁻⁵) is appro...

Calculate [H+] (in mol L⁻¹) after mixing 25 mL of 0.040 M HCl with 75 mL of water (assume volumes ad...

The conjugate acid of (CH3)3 N is:

Which factor most strongly determines whether an amphoteric species acts as an acid or a base in wat...

A 0.10 M solution of a weak base B has Kb = 2.5×10⁻⁴. The pOH of the solution is approximately:

About This Question