A mixture contains 25.0 mL of 0.0100 M and 25.0 mL of 0.0100 M
CHEMISTRY · Multi-part · AP · Chemistry · Acids and Bases · Acids and Bases
Problem
A mixture contains 25.0 mL of 0.0100 M Al3+ and 25.0 mL of 0.0100 M Fe3+. The combined solution is buffered at pH 4.00 with an acetate buffer (the buffer capacity is large enough that the pH remains effectively constant). Relevant data at 25 °C: Ksp(Al(OH)3)=3.0×10−34 and Ksp(Fe(OH)3)=2.6×10−39.
(a) For each cation, calculate the concentration of hydroxide ion required for the ion product Q to equal Ksp.
(b) Using the fixed pH of the solution, determine whether either hydroxide solid will precipitate under the buffered conditions.
(c) If an additional 0.0020 mol of sodium acetate were added without changing volume, predict qualitatively (no calculations required) whether your answer to part (b) would change and explain why or why not.