How can we calculate the pH of a solution if we dilute with water?

[Arie Hakimi 1L]

How can we calculate the pH of a solution if we dilute with water?

For example, if we assume that we have a weak monoprotic acid (pKa = 5.76, Ka= 1.74x10^-6),

How would we calculate the pH after we take a 5 mL sample of 0.010 M weak acid, and dilute it with 45 mL of water?

[Lauren Trent 2A]

If you're referring to the 14BL study questions, you use the original molarity given (0.010M) and do the M1V1=M2V2 calculation for the dilution to find the molarity of the solution first.
So it would be: (5mL)(0.010M)=(50mL)(M)
Once you solve for the molarity, you follow the same procedure you did for part a of the question and find the concentration of just hydrogen ions with this different molarity of acid using an ICE box, then take the -log of the concentration of H+ ions to find the pH, also like you did for part a.
Hope this helps!