NH4^+ is the only one hydrolyzed. You know NO3^-, Cl^- and K^+ are not hydrolyzed BECAUSE those hydrolysis products would be STRONG acid/bases. For example,
Cl^- + HOH ==> HCl + OH-
or
K^+ + HOH ==> KOH + H^+
and that doesn't happen. Why NH4^+? BECAUSE it forms a WEAK base.
NH4^+ + H2O ==> NH3 + H3O^+ and that is why solutions of NH4Cl and the like are acidic in solution.
Acetate ion is hydrolyzed because it forms a WEAK acid.
C2H3O2^- + HOH ==> HC2H3O2 +OH^- and that's why solution of sodium acetate or potassium acetate are basic in solution.
I'll post later on #2.
1) Which ion(s) below would undergo hydrolysis in water?
A) Cl-
B) K+
C) NH4+
D) NO3-
E) Two of the above
My guess is C, but I'm not too sure about this one.
2) Calculate the [OH-] present in solution labeled 1.73 M methylamine. CH3NH3 + H2O --> CH3NH3+ + OH-.
I get 2.76 x 10^-2 for this, but again, not entirely sure.
3 answers
You made a typo in th equation. It should be
CH3NH2 + HOH ==> CH3NH3^+ + OH^-
I obtained 2.9E-2 for OH^- but we may not have used the same Kb. I used 5E-4.
CH3NH2 + HOH ==> CH3NH3^+ + OH^-
I obtained 2.9E-2 for OH^- but we may not have used the same Kb. I used 5E-4.
Right. I typed it correctly, so it's definitely a typo on the worksheet. Thanks for pointing that out.
I used 4.4 x 10^-4 for Kb, per my textbook.
Thanks for checking!
I used 4.4 x 10^-4 for Kb, per my textbook.
Thanks for checking!