In a certain experiment a student finds that the PHs of 0.10 M solutions of three potassium salts KX, KY, and KZ are 7.0, 9.0, and 11.0, respectively. Arrange the acids HX, HY, and HZ in order of increasing acid strength.

Answer 1

Write the hydrolysis equations. For x it will be
........X^- + HOH ==>HX + OH^-
I......0.1...........0.....0
C......-x............x.....x
E.....0.1-x..........x.....x

Kb for X^- = (Kw/Ka for HX) = (x)(x)/).1-x
Since pH = 7 that makes pOH = 7 and (OH^-) = x = 1E-7. Solve for Ka. You may need to use the quadratic.

Do the same for Y and Z salts, solve for Ka for HY and HZ then you will have
Ka for HX, HY, and HZ and arrange them in order of increasing acid strength which will be in order of increasing Ka.