Question

I need help solving this problem.
The pH of a substance is 6. What is the molarity of the [H3O+]?
Select one:
a. 6.0 M
b. 6.0 x 101 M
c. 1.0 x X-6 M
d. 1.0 x 106 M

Answer 1

what's the relationship between concentration of H+ and pH? There are 2 useful equations

Answer 2

pH=-log[H+]

Answer 3

@JFraser

Answer 4

do you know how to rearrange that to solve for [H+]?

Answer 5

I do not

Answer 6

Is it [H+]=10^-pH

Answer 7

If it is I plugged in 6 for pH. [H+]= 10^-6 and got 0.000001. I logged it and got -6.

Answer 8

@abb0t

Answer 9

If you know that [H\(^+\)] = 10\(\sf^{-pH}\), than all you have to do is plug it in. Which you did. Why are you asking.

Answer 10

Because I am not fully sure if i am correct. I would like to be sure if i am correct so i won't get the question wrong. That one question is worth 12.5 points. Its worth more than half the the assignments that I have to do in this course.

Answer 11

I am not sure if I am suppose to negate the -6 to make it positive and get either A or B. If I am not suppose to then the answer is C. I know for a fact that the answer is not D.

Answer 12

the "extra" negative is taken care of in the equation: 10^(-pH), and -log(H+).

the pH is 6, so 10^(-pH) is 10^(-6)

Answer 13

-log(10^(-6)) is -log0.000001=6. So the answer is 6.0M

Answer 14

when you take the log of the concentration, you get pH, which is the original value.

the 2 functions are inverses of each other. 10^(-pH) gets you concentration, and -log[H+] gets you pH. Your first answer was correct, the concentration is 10^-6M

Answer 15

I see now. Thank you @JFraser :)