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### Topic: pH  (Read 3030 times)

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#### kapital

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##### pH
« on: October 24, 2009, 07:43:48 AM »
I have problems with this: How many grams NaOH we must put in 200mL  1M HCl, if we want to get the solution with pH=13?(alpha=1, volume is not changed)

I start at first how much NaOH neutralize all HCl, that is 8 grams. Now ph=7.

And now ph(x-molar NaOH)=13,5

I have no idea how get x form this. I hope someone can help and really sory form my bad english

#### Borek

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##### Re: pH
« Reply #1 on: October 24, 2009, 08:42:06 AM »
pH + pOH = 14
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#### kapital

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##### Re: pH
« Reply #2 on: October 24, 2009, 08:45:40 AM »
I know that. But i sont know how to save this equation -log(x)=13,5

#### Borek

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##### Re: pH
« Reply #3 on: October 24, 2009, 09:52:10 AM »
So you were told to use logarithms but you were not told what they are? Hard to believe.

http://en.wikipedia.org/wiki/Logarithm
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#### kapital

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##### Re: pH
« Reply #4 on: October 24, 2009, 02:03:04 PM »
If there would not be minus it woud be 10 ON 13,5=X. Since there is -, i do not know how to do it.

#### Borek

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##### Re: pH
« Reply #5 on: October 24, 2009, 03:22:01 PM »
-log(x)=13,5 => log(x)=-13,5

Does it help? If not, your problem is not chemistry, but math, and you should really spend some time working on it.
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