Question

5. Which of the following solutions has the highest pH? *
1.0 M Li2SO4
1.0 M CuF2
1.0 M NH4Br
1.0 M K2CO3

Answer 1

I'll show a couple of these and you do the others.
Li2SO4:
SO4^2- + HOH ==> HSO4^- + OH^-
1.0...............................0................0
-x.................................x.................x
1-x.................................x..................x
Kb for SO4^2- = Kw/K2 for H2SO4 = (x)(x)/(1-x)
Solve for x = (OH^-) and convert to pH.

NH4Br:
NH4^+ + H2O ==> NH3 + H3O^+
1.0.............................0...........0
-x................................x...........x
1-x.................................x...........x
Ka for NH4^+ = (Kw/Kb for NH3) = (x)(x)/(1-x)
Solve for x = (H3O^+) and convert to pH.
Do the others the same way and compare pH within the set.

Answer 2

Thank you!