Monday, November 22, 2010

How we can vary the pH value of an acid?

Here for growing single prganic crystal i want to change the pH value(increase) so how it cn be done.How we can vary the pH value of an acid?
Vary the amount of water it is dissolved in. pH is the concentration of the H+. Change the concentration and you change the pH. Of course, that might require a lot of water, so another method of controlling the amount of H+ would be to neutralize some of them with some OH- (add a base). Of course adding waer or adding a base would only increase the pH. To lower the pH you could add an acid or remove some water by evaporating it. You can't just pour some off, because that would also carry off some of the H+.How we can vary the pH value of an acid?
....dont add a base i know that...

but increase...sorry no idea
The solution in which you are working with must be having a constant pH, that you know by dipping the pH electrode. So if you need to keep it constant so as to carry out the chemical process (precipitation, Crystallization), just add the same acid that you added to have that pH of the solution. But the solution you are adding must be dilute as compared to the previous solution, because it will make the solution up to the required pH comfortably by adding it drop wise. If more concentrated then it may cross the pH limit that is required. So be careful and add it slowly and monitor the pH while adding, also shake it slowly, or stir it to make it uniform. Similarly you can increase also, go on adding the dilute acid solution to the mixture/ solution and monitor the pH with pH meter. Hope this will work.
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