Wednesday, November 17, 2010

How much acid solution is needed to change the pH by 0.1 pH units?

If a buffer is made up to be 1.0M in acetic acid and 1.0 M in sodium acetate, predict how much acid will be required to change the pH of 100mL of the buffer by 0.1 pH units.

I already calculated that the pH will be around 4.75 initially.How much acid solution is needed to change the pH by 0.1 pH units?
moles acetic acid = moles acetate = 0.100 L x 1.0 M = 0.100



we need a pH of 4.65



4.75 - 4.65 =0.1



pKa = 4.75



4.65 - 4.75=- 0.1

10^-0.1 =0.79 = [acetate]/ [acetic acid] = 0.100-x/0.100+x



0.079 + 0.79 x = 0.100-x

0.021 = 1.79 x

x = 0.0117 moles of acetic acid neededHow much acid solution is needed to change the pH by 0.1 pH units?
can someone please explain this will a little more detail. I'm not getting where all of these numbers are coming from? Thanks

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