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### 2007 Final Question 5B

Posted: Sat Dec 03, 2016 10:26 pm
Given: N2O4 (g) $\rightleftharpoons$ NO2 (g)
What are the equilibrium partial pressures of N2O4 and NO2 when 0.20 mol of N2O4 and 0.80 mol of NO2 are sealed in a 2.00 L container at 100 degrees Celsius. When the reaction reaches equilibrium at 100 degrees Celsius, Kp= 11.0.

The solution in the book calculates Q, and I was wondering why this was necessary? Thanks!

### Re: 2007 Final Question 5B

Posted: Sat Dec 03, 2016 10:29 pm
Did the solution also calculate Kp? It could be that the solution is trying to test if the reaction is at equilibrium or not. Q and Kp are calculated the same way, so calculating Q would theoretically be like calculating Kp if only a single condition/ state of the reaction is given. Either way, the answer would be the same (although be careful, because the meaning of Q and Kp differ).

### Re: 2007 Final Question 5B

Posted: Sat Dec 03, 2016 10:38 pm
No, Kp was given. The solution includes Q to find the direction in which the reaction proceeds. However because the question doesn't explicitly state to solve for Q, I was wondering if it was necessary.