## 5I.9

JamieVu_2C
Posts: 108
Joined: Thu Jul 25, 2019 12:16 am

### 5I.9

For the reaction H2(g) + I2(g) $\rightleftharpoons$ 2 HI(g), K=160. at 500. K. An analysis of a reaction mixture at 500. K showed that it had the composition PH2 = 0.20 bar, PI2 = 0.10 bar, and PHI = 0.10 bar. (a) Calculate the reaction quotient. (b) Is the reaction mixture at equilibrium? (c) If not, is there a tendency to form more reactants or more products?

For a, the reaction quotient will be Qp since the gasses are given as partial pressures. In part b, when comparing Qp to the K given, how do you know if the K given is Kc or Kp, or do we just assume that the K is automatically Kp since the problem gave us the partial pressures of each species? In general, is that what we should assume with the textbook as well in the tables if there is a separate column for K and another column for Kc?

Connor Ho 1B
Posts: 102
Joined: Sat Aug 17, 2019 12:17 am

### Re: 5I.9

In this specific problem, I would assume that the K is Kp since the partial pressures are measured. I think that for the tables, the K would have to be inferred as Kp, although Lavelle said in class that K is often used as another way to infer Kc and Kp.

JasonLiu_2J
Posts: 109
Joined: Sat Aug 24, 2019 12:17 am

### Re: 5I.9

I think that since the problem gives the reactants and products in terms of partial pressures, the given K value will also refer to Kp. Generally, the K value should correspond to the units given in the problem unless it is specifically stated in the question that K is either Kp or Kc.

HuyHa_2H
Posts: 100
Joined: Wed Sep 11, 2019 12:15 am

### Re: 5I.9

I'd assume that it'd be Kp because units of pressure is given, but I don't think it should be too concerning because you can convert between concentration and pressure anyways.