The ionic product of water ( ) at is

CHEMISTRY · Multi-part · A Level · Chemistry · Acids and bases · Acids and bases

Problem

The ionic product of water (

K_w

) at

40\,^{\circ}\text{C}

3.00\times10^{-7}

, differing from its value at

25\,^{\circ}\text{C}

. A chemist prepares a 0.0100 M KOH solution and maintains it at

40\,^{\circ}\text{C}

. (1) Part 1: Determine the molar concentration of hydroxide ions in the solution at

40\,^{\circ}\text{C}

. (2) Part 2: Calculate the pOH of the solution at

40\,^{\circ}\text{C}

. (3) Part 3: Using the provided value of

K_w

, calculate the pH of the solution at

40\,^{\circ}\text{C}

. (4) Part 4: Calculate what the pH of the same 0.0100 M KOH solution would be if it were instead held at

25\,^{\circ}\text{C}

. (5) Part 5: Explain, in terms of

K_w

, why pH and pOH no longer sum to 14 at

40\,^{\circ}\text{C}