Calculate hydroxyl ion concentration, ph and the percent hydrolysis for 0.1M solution of sodium cyanide (hints know for cyanide ion is 2.5*10^-5).

Answer 1

I don't understand the hint. What's know. I assume that is some K for cyanide and my best guess is that is Ka for HCN. Here is how you do it knowing Ka.
..............CN^- HOH ==>HCN + OH^-
I.............0.1........................0..........0
C.............-x........................x...........x
E,,,,.......0.1-x......................x...........x

Kb for CN^- = (Kw/Ka for HCN) = (x)(x)/(0.1-x)
Substitute and solve for x = (OH^-). Convert that to pH .
%hydrolysis = [(OH^-)/0.1]*100