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Topic: calculating concentration from pH  (Read 51684 times)

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Offline curiousgeorge1234

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calculating concentration from pH
« on: February 09, 2007, 02:00:36 PM »
I know how to calculate pH: -log [H+] for example.

But, if you are given the pH, ie. pH -1.00, how do you calculate the concentration?

Offline Dan

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Re: calculating concentration from pH
« Reply #1 on: February 09, 2007, 02:43:48 PM »
Law of logs. log(x) usually (and in this case) is log10(x)

if log(x) = y

x = 10y
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Offline curiousgeorge1234

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Re: calculating concentration from pH
« Reply #2 on: February 09, 2007, 03:04:46 PM »
so, if the pH is -1.00

x= 10^ -1

is that correct?

Offline Dan

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Re: calculating concentration from pH
« Reply #3 on: February 09, 2007, 03:05:36 PM »
Careful, pH = -log[H] remember
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Offline curiousgeorge1234

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Re: calculating concentration from pH
« Reply #4 on: February 09, 2007, 03:07:06 PM »
then, x = 10^1

Offline Dan

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Re: calculating concentration from pH
« Reply #5 on: February 09, 2007, 03:08:11 PM »
yes
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Offline yolop

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Re: calculating concentration from pH
« Reply #6 on: February 14, 2007, 04:37:28 PM »
Last time I checked the pH scale was 0-14.  -1 should be wrong unless you just made it up. 

to calculate pH from a [H] or [OH-] you take the antilog.

Offline enahs

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Re: calculating concentration from pH
« Reply #7 on: February 14, 2007, 09:38:52 PM »
A negative number for a pH is perfect legit.

And you are right about the antilog. But what happens if you take the antilog of 1? You get 0. If you take the antilog of 2, you get a negative number. Are you saying it is impossible to have 2 Molar concentration of an acid?


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