chemistry
posted by Sevwerl .
the Ph of a solution of HCl in water is found to be 2.50. what volume of water would you add to 1.00 L of this soltuion to raise the PH to 3.10?
I think I'm supposed to use the formula C1V1=C2V2 but where would i get the concentrations from?

From the pH.
pH = log(H^+). You know pH, calculate (H^+), then use your CV formula. Note, however, that the questions asks what volume of water is to be ADDED (not what is the final volume). Do your CV formula to find the total volume, then subtract from 1.00 L to find the amount to add.