Calculate the hydronium ion concentration of blood which has a pH of 7.24.

Question

7.17 x 10-4 M
5.75 x 10-8 M
1.15 x 10-7 M
0.86 M
none of the above

I had chose 1.15*10^-7 by doing the log equation -log(1.15...) and I but it goether with -log(10*^-7.24) and it was closest to 14 and that's how I thought you were supposed to do this question. But, when I put 5,75*10^-8 in that equation it gives me 7.24. Is that the answer?

Answer 1

Yes, 5.75E-8 is the answer for pH = 7.24.
You should do pH = -log(H3O^+), then
7.24 = -log(H3O^+)
-7.24 = log(H3O^+)
(H3O^+) = 10^-7.24 = 5.75E-8