The pH of a certain specimen of urine is 4.8. What is the hydroxide ion concentration, [OH^-], of this solution?

Question

Quizplus · Accepted Answer

The pH of the urine specimen is 4.8, which means the hydrogen ion concentration ([H+]) is 10^-4.8 M. 
Using the equation for the dissociation of water, we can find the hydroxide ion concentration ([OH-]):
Kw = [H+][OH-] 
1.0 x 10^-14 = (10^-4.8)[OH-] 
[OH-] = (1.0 x 10^-14) / (10^-4.8) 
[OH-] = 6.3 x 10^-11 M 
Therefore, the hydroxide ion concentration is 6.3 x 10^-11 M, which corresponds to choice B.

The PH of a Certain Specimen of Urine Is 4