A buffer solution is prepared by adding 14.37g of NaC2H3O2 and 16.00g of acetic acid to enough water to make 500mL of solution.

Question

What is the initial concentration of C2H3O2 in the solution?

Ka(HC2H3O2)=1.8e-5

HC2H3O2 = H3O+ + c2h3O2

the molar mass of NaC2H3O3 = 82.04

I know that m=mol NaC2H3O2 / L
so would I do 82.04 / .05?

Answer 1

You don't know that m = mol NaC2H3O2/L; because m stands for molality. You may know that M = mol NaC2H3O2/L since that is molarity.
mols NaC2H3O2 = grams/molar mass
mols HC2H3O2 = grams/molar mass
M of each = mols/0.500 L

Then pH = pKa + log(base)/(acid).