This question is about weak acids and buffer solutions.
Glycolic acid, CH2(OH)COOH\text{CH}_2(\text{OH})\text{COOH}CH2(OH)COOH, is a weak monobasic acid.
Explain what is meant by the term weak monobasic acid.
A buffer solution is prepared by dissolving 0.800 g0.800\text{ g}0.800 g of sodium hydroxide, NaOH\text{NaOH}NaOH, in 250.0 cm3250.0\text{ cm}^3250.0 cm3 of 0.240 mol dm−30.240\text{ mol dm}^{-3}0.240 mol dm−3 glycolic acid.
This buffer solution has a pH of 3.533.533.53 at 25∘C25^\circ\text{C}25∘C.
Calculate the acid dissociation constant, KaK_aKa, of glycolic acid at 25∘C25^\circ\text{C}25∘C.
Assume that the volume of the solution remains constant at 250.0 cm3250.0\text{ cm}^3250.0 cm3 when the sodium hydroxide is dissolved. Give your answer to 3 significant figures.
Ka=K_a = Ka= ........................................ mol dm−3\text{mol dm}^{-3}mol dm−3
When a small volume of water is added to this buffer solution, the pH does not change.
Explain why the pH does not change.
