[Gammagirl]

A solution was prepared by dissolving 0.0170 mole of propionic acid and 0.0179 mole of sodium propionate in 1.00 L

What would be the pH of the solution in beaker after 2.00 mL of 0.0154 M HCl were added to 10.0 mL of the prepared solution?
 
NaC3H5O2=.0179mole/1000ml=.000179 mole per 10ml
HC3H5O2=.0170mole/1000ml=.000170 mole per 10ml
volume of acid added= .002 L x .0154mole/L=.0000308 mole
   C3H5O2-     +       H3O+--------> HC3H5O2      +      H20
I .000179         .0000308              .000170
C-.0000308    -.0000308             +.0000308
E .0001482           0                      .0002008

pH= 4.89 +log .0001482/.000208               Ka= 1.3 x 10^-5
pH=4.76

Can someone please help me with this problem? Is the answer correct, please?

[Borek]

You have to show your attempts at solving the problem to receive help, this is a forum policy.

[wildfyr]

Well she did put up the ICE table and arithmatic, so an attempt to solve is there. How about this Gammagirl, why did you come to the forum to ask this? What makes you think the answer is wrong?

[Babcock_Hall]

Your answer is close.  Check your math.

[Gammagirl]

I still get 4.76?  I beseech you.  (Taking sig figs to the end, I arrived at 4.75?)

[Babcock_Hall]

When I took the logarithm of 0.0001482/0.000208, I obtained a slightly different answer, different by about 0.02 of a pH unit.  The problem is the difference between 0.000208 and 0.0002008.  In other words, you may have a transcription error in what you wrote near the bottom of your answer.

[Gammagirl]

Yes, that is a transcription error, but I did take the log of .0001482/.0002008 .  Is 4.75 the better final answer?

[Babcock_Hall]

I think that 4.76 is fine.  The problem that I encountered was that when I used 0.000208, then I obtained 4.74.

[Borek]

Well she did put up the ICE table and arithmatic, so an attempt to solve is there.

That was added in an edit, not a part of the original post.

4.76, 4.75 - the difference doesn't matter, the real pH will be off either way because of the thermodynamic effects, so there isno need to worry.

[Gammagirl]

Grateful, Γgirl