Question

what is the pH of 100 mM HCl?

Answer 1

100mM = 10*10^-4 OR 1*10^-3
[H+] = 1*10^-3
pH = -log 1*10^-3
pH = 6.90

Answer 2

? - how did you get 6.9???

Answer 3

shouldnt it be 3?

Answer 4

Oh, you're right. It should be 3. My mistake. I should of known it was wrong. a pH of almost 7 for HCl makes no sense :P

Answer 5

I don't get why it should be three - surely the pH is the -log10 of the H+ concentration so it's log10(0.1) =-1 so pH = 1. If it was 1M HCl the pH woould be 0, since log 10 of 1 is 0. pH=3 if the concentration of H+ is 1mM surely?