A laboratory technician prepares an aqueous solution by mixing exactly 0.100 mol of…
CHEMISTRY · Multi-part · A Level · Chemistry · Acids and bases · Acids and bases
Problem
A laboratory technician prepares an aqueous solution by mixing exactly 0.100 mol of acetic acid, CH3COOH, with 0.100 mol of ammonia, NH3, and diluting the mixture to a final volume of 1.00 L at 25 °C. Selected data are provided below.
• Ka(CH3COOH) = 1.8×10−5
• Kb(NH3) = 1.8×10−5
• Kw = 1.0×10−14 at 25 °C
Assume all solutions behave ideally.
(a) Write the net ionic equation for the reaction that occurs when the acetic acid solution is mixed with the ammonia solution.
(b) Using the numerical values provided, describe whether the resulting solution is expected to be acidic, neutral, or basic at 25 °C. Justify your prediction qualitatively without performing a full numerical pH calculation.
(c) Suppose the technician instead mixed equimolar quantities of formic acid, HCOOH (Ka=1.8×10−4), with ammonia under the same conditions. Explain how and why the predicted pH classification would change, if at all.