Solgn slogan

BaCl2 +H2SO4 = BaSO4+2HCl, it can be seen that the amount of H+ substance has not changed before and after the reaction.

N (h+) = cv = 0.5 * 0.001* 2 = 0.001(mol)

C (h+) = n/v = 0.001(0.5+0.5) = 0.001(mol/l)

PH =-Lgn（H+）= 3