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obama obama
wrote...
Posts: 60
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11 years ago
How do you calculate the hydrogen ion concentration of an aqueous solution, given the pOH of the solution is 4.50 and the ion product constant for water, Kw, is 1.00 x 10-16?

a. 3.16 x 10-10 M
b. 3.16 x 10-9 M
c. 3.16 x 10-5 M
d. 3.16 x 10-7 M
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wrote...
11 years ago
To find Ph, you do 14-pOH= 9.5

10^-ph= Hydrogen ion concentration
so 10^-9.5= 3.16 x10^-10
wrote...
11 years ago
To start, the value of Kw is 1.00 x 10^-14, not 1.00 x 10^-16. And you cannot alter this constant, because its a constant.

But to answer your question... we can use the following steps.

-log(pOH) = OH^-1

So we should start by saying:

a) -log(4.50) = OH^-1

So the answer to this is

a) OH^-1 = -0.65

Now that we have OH^-1, we can use our formula.

Kw = [H3O+][OH-]

We know Kw = 1.00 x 10^-14 and OH^-1 = -0.65

So..

a) 1.00 x 10^-14 = [H3O+][-0.65]

I don't have a calculator on hand, but this is what you would plug in:

(1.00 x 10^-14)/(-0.65) = Your answer

If you persist that Kw = 1.00 x 10^-16, this is what you'd plug in:

(1.00 x 10^-16)/(-0.65) = Your answer

Hope this helps.
wrote...
11 years ago
so to get the H concentration you need to have pH, which you can get from the pOH by using pH+pOH= 14 so 14-4.5=9.5. then you can get the concentration by taking 10^-(pH) *make sure you put in the negative

I get a 3.16x10-10M
wrote...
11 years ago
pH + pOH= 14

pOH= -log[OH-]

kw= [H3O+][OH-]=1*10^-14
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