BaCl2 +H2SO4 = BaSO4 + 2HCl 从中可以看出,反应前后H+的物质的量没变.
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