Topic: Calculating pH of buffer solution (Read 9284 times)

kad3285 · « **on:** July 07, 2005, 10:25:08 AM »

I need some help calulating the pH of a 100mL solution, at .025M (w/ pkb=4.76) and .075 M ammonium acetate with 1mL of .1 F HCl is added...

I am a little confused with calculating the pH after the addition of another solution.

Can someone point me in the right direction?

lemonoman · « **Reply #1 on:** July 07, 2005, 10:36:42 AM »

Think of it as a titration of base with acid. Then, at the end, there will be either an excess of base (CH₃COO^-), excess of acid (H⁺), or an excess of neither (perfect equivalence point).

Then you can figure things out from there, whether you want to treat the solution as basic or acidic.

Good luck!

P.S. Try searching the forum for similar questions - Buffers are a popular topic in Highschool, and it's almost certain to have been covered before. To start off, try

http://www.chemicalforums.com/index.php?board=6;action=display;threadid=3626

and then do a search here

http://www.chemicalforums.com/index.php?action=search

kad3285 · « **Reply #2 on:** July 07, 2005, 10:41:54 AM »

This is what I did to find the standard

pH = 4.76 + log (.025)/(.075) = 4.283
.

Now I just treat the addition of HCl as a dilution right?

Borek · « **Reply #3 on:** July 07, 2005, 12:25:45 PM »

Quote from: kad3285 on July 07, 2005, 10:41:54 AM

Now I just treat the addition of HCl as a dilution right?

No. Adding hydrochloric acid you are converting conjugated base (acetate) into acid (acetic acid).

Take a look here:

http://www.chembuddy.com/?left=pH-calculation&right=pH-buffers-henderson-hasselbalch

and here:

http://www.chembuddy.com/?left=pH-calculation-questions&right=pH-buffer-q1

Topic: Calculating pH of buffer solution (Read 9284 times)

kad3285

Calculating pH of buffer solution

lemonoman

Re:Calculating pH of buffer solution

kad3285

Re:Calculating pH of buffer solution

Borek

Re:Calculating pH of buffer solution

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