## 2010 Q4B How to get the Q

$E_{cell} = E_{cell}^{\circ}-\frac{RT}{nF}\ln Q$

Kiara1F
Posts: 64
Joined: Fri Sep 25, 2015 3:00 am

### 2010 Q4B How to get the Q

My particular question : how did they come up with Q? I know Q is product/ reactant

HA --> H+ A-

But in the problem it says " because in a buffer system (A ) = (HA) we can write Q =(H+)
Why is this?

Problem for reference:
"When a PH meter was standardized with a boric acid- borate buffer with a pH of 9.40, the cell emf was 0.060V. When the buffer was replaced with a solution of unknown hydronium ion concentration, the cell emf was 0.22V. What is the pH of the solution?
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Milan Hirpara 3K
Posts: 20
Joined: Sat Jul 09, 2016 3:00 am

### Re: 2010 Q4B How to get the Q

(A- = HA) because there is a buffer involved. Whenever a buffer is involved you can assume (A- =HA).

Return to “Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)”

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