A sample of HF ( ) is at equilibrium at

CHEMISTRY · Single correct · A Level · Chemistry · Acids and bases · Acids and bases

Problem

A 50.0 mL50.0\,\text{mL} sample of 0.10 M0.10\,\text{M} HF (Ka=6.6×10−4K_a = 6.6\times10^{-4}) is at equilibrium at 25∘C25^{\circ}\text{C}. Pure water is added to bring the total volume to 500.0 mL500.0\,\text{mL}. Which of the following best describes the change in pH after the dilution is complete and equilibrium is re-established? (a) The pH increases by approximately 1.01.0 unit. (b) The pH decreases by approximately 0.500.50 unit. (c) The pH increases by approximately 0.500.50 unit. (d) The pH changes by less than 0.050.05 unit and is effectively unchanged.

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