Question

If the OH ion concentration in an aqueous solution at 25 celsius is 3.4x10^-3 M the the H concentration in moles per liter in the same solution is?
answers is 2.9x10^-12

i do the -log and i get 2.46 i don't know that else

Answer 1

The problem asks for (H^+) and I see 2.9E-12 on my calculator. You must be punching in the wrong numbers.

Answer 2

so i do the -log(3.4x10^-3)=2.46

Answer 3

No, you are making two errors.
#1. The problem asks for (H^+) and gives you the (OH^-). So
(H^+)(OH^-) = Kw = 1E-14
(H^+) = 1E-14/(OH^-) = 1E-14/(3.4E-3) = 2.94E-12 which rounds to 2.9E-12 to two significant figures. That's the answer.
#2. You are using the value of OH as the value for H^+ AND you're changing that to pH which it doesn't ask for.

Answer 4

ok thanks