posted by Kaleen .
A 11.8 mL sample of a HCl solution has a pH of 2.000. What volume of water must be added to change the pH to 4.000?
pH = 2; convert to H^+ (which will be concn in moles/L = M). Convert pH 4 to H^+. Then
mL1 HCl x M1 HCl = mL2HCl x M2HCl