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Buffer adding common ion effect?

  • Thread starter Raul3140
  • Start date
  • #1
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Homework Statement



What will be the pH of a solution that contains 0.100 M CH3COOH and 0.100 M NaCH3COO?Ka = 1.8x10-5
IMPORTANT: THE REACTION IS NOT BETWEEN CH3COOH AND CH3COO-

- My question here is why the ice table was setup as so by the instructor? see below...



Homework Equations





The Attempt at a Solution



CH3COOH + H20 ---> CH3COO- + H3O
.100M-x .100m+x +x

Where did the Na go? Why did the Molarity of NaCH3COO = Molarity of CH3COO- ????
 

Answers and Replies

  • #2
Borek
Mentor
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My question here is why the ice table was setup as so by the instructor? see below...
No idea. No need for an ICE table. You can safely assume concentrations of both acid and conjugate base are these introduced into solution.

Where did the Na go?
Doesn't matter, Na+ is just a spectator.

Why did the Molarity of NaCH3COO = Molarity of CH3COO- ????
Dissociation stoichiometry, plus the assumption explained above.

Compare Henderson-Hasselbalch equation.
 

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