Household vinegar (an aqueous solution of acetic acid, ) is accidentally spilled onto…
CHEMISTRY · Subjective · A Level · Chemistry · Acids and bases · Acids and bases
Problem
Household vinegar (an aqueous solution of acetic acid, CH3COOH) is accidentally spilled onto a kitchen surface coated with baking soda (sodium bicarbonate, NaHCO3). The surface is then rinsed with tap water, allowing all reactants and products to mix.
(a) Write a balanced net ionic equation for the principal proton-transfer reaction that occurs when the spilled vinegar comes into contact with the bicarbonate on the surface.
(b) Identify the conjugate acid–base pair formed in the reaction written in part (a).
(c) A second plausible proton-transfer equation could be written involving CH3COOH and the carbonic acid, H2CO3, that forms transiently during the interaction. Write this alternative equation and state whether it is likely to proceed to any significant extent under the conditions of the spill. Support your answer with one clearly stated piece of chemical reasoning.
(d) Assuming excess vinegar was present and the rinsing water merely diluted the mixture without introducing additional acid or base, predict qualitatively (acidic, basic, or approximately neutral) the final pH of the rinse water left on the surface after vigorous bubbling has ceased. Explain your reasoning in one or two well-organized sentences.