Titration of 12.50 mL of HCl solution requires 22.50 mL of 0.1250 M NaOH solution. What is the molarity of the HCl solution?

Answer 1

HCl + NaOH ==> NaCl + H2O

mols NaOH = M x L = ?
mols HCl = mols NaOH (look at the coefficients; 1:1)
Then M HCl = mols HCl/L HCl.