An unknown diprotic acid requires 26.66 mL of 0.117 M NaOH to completely neutralize a 0.845 g sample. what is the molar mass of the acid?

1 answer

Look at the problem with KHP. All of these are essentially the same.
Step 1 is mols standard solution (the one with BOTH M and L)
Step 2. Use the coefficients in the balanced equation to convert mols of what yu have to mols of what you want.
Step 3. Use the definition of M = mols/L
And by the way, you will notice steps 1, 2 and 3 are the same when you do stoichiometry problems.

H2A + 2NaOH ==> Na2A + 2H2O
mols NaOH = M x L = ?
mols H2A = 2x mols NaOH from the coefficients in the balanced equation.
M H2A = mols H2A/L H2A