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Topic: pH increase  (Read 3011 times)

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Offline ziagemini

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pH increase
« on: May 15, 2012, 03:54:41 PM »
Hello All,

I have a a solution of CaCO3 and acetic acid in 1L solution i.e. 2g CaCO3 and 1ml Acetic acid. The pH of this solution is 6.3. How can i increase the pH of this solution till 7.5 without disturbing the original solution. Is it OK to add NaOH to this solution or what can i add to increse the pH??

Thanks for the help.

Regards!

Offline Arkcon

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Re: pH increase
« Reply #1 on: May 15, 2012, 05:40:37 PM »
The definition of "disturbing" will depend on your application.  You have a small amount of CaCO3 and an even smaller amount of acid.  If you add anything, you'll have less of each ... is that a problem.  If you raise the pH, you will do that by neutralizing acid ... if you don't want the solution to be acid, why add it?  You have a dilute solution of Ca2+ and acetate- ions, after neutralizing with NaOH, you'll also have Na+ ions, will that be a problem?  That would be if this were a solution for feeding terrestrial plants hydroponically, as an example.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline ziagemini

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Re: pH increase
« Reply #2 on: May 16, 2012, 08:31:48 AM »
Hello,

By disturbing i means the buffers i.e. without effecting the buffering action of Acetate and Carbonate can i add NaOH?
Or what can i add so it don't disturb the buffer capacity of any of the following.

Regards!

Offline Arkcon

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Re: pH increase
« Reply #3 on: May 16, 2012, 08:37:30 AM »
If you take the pH outside of (about) 1 pH unit from the pKa, then you no longer have a buffer, no matte how you get there.  I don't know, offhand, the pKa of [carbonate], this is kinda hard to know ... since the reaction produces CO2 gas, if any escapes the solution, the concentration changes, altering pH.  Living things use a carbonate buffer system, but they have a way to control dissolved CO2.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

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