[szh122]

I have been having trouble with these questions. Any help is much appreciated. Thanks in advance.

Phenoparbital, HC12H17N203, is generally administered as the sodium salt. What is the Ka of the acid if a solution of NaC12H17N2O3 that contains 65 mg of the drug in 500ml of solution has a pH of 9.3

I'm not sure if this is right but what I did was get the weight of the phenoparbital which was 237g, then I converted 65 mg to .065 grams. Divided .65 grams by 237 and got 2.74 x 10-4 which I then divided by 5 Liters to get 5.49 x 10-5 for the molarity of phenoparbital. Once I got that I did the inital, change and equilibrium of the reaction
C12H17N203 + H20 -----> HC12H17N2O3 + OH-
I then got the pOH by subtracting the 14-9.3= 4.7
I'm not sure where to go from there but the numbers do not seem correct. Thanks.



I have no idea how to approach this question.

A solution of .035 M KCN is found to be hydrolyzed to the extent of 17%. Calculate the value of ionization constant for HCN from the value you obtain for the hydrolysis of KCN.