Question

20ml H2SO4 and 10ml HCl can be neutralized by 20ml NaOH (0.1M) separately.Calculate the pH of the acids?

Answer 1

HCl + NaOH ==> NaCl + H2O
mols NaOH = M x L = 0.1 x 0.02 = 0.002.
mols HCl = 0.002 from the coefficients in the balanced equation.
M HCl = mols/L = 0.002/0.02 = 0.1M HCl. Convert to pH. pH = -log(H^+).

H2SO4 + 2NaOH ==> 2H2O + Na2SO4
mols NaOH = M x L
Using the coefficients in the balanced equation, convert mols NaOH to mols H2SO4.
Then M H2SO4 = mols H2SO4/L H2SO4.
molarity H^+ = ?
Then convert to pH.
Post your work if you get stuck.