64 GC destroyer - Kp problem

[Kneecoal]

---

Members don't see this ad.

i'm hoping someone can explain this...

2A(g) + B(g) <---> 2C(g)

0.5 atm of A and 0.2 atm of B are placed in a flask at 300K. At equilibrium, the total pressure is 0.6 atm. Calculate Kp.

So I set it up so that A = 0.5 - 2x and B = 0.2 - x... but I don't understand why they also place the 2x of C on the left side to give:

(0.5 - 2x) + (0.2 -x) + 2x = 0.6

Why wouldn't the 2x go on the right side?

 

[GOLF]

theyre actually setting up the expression to equal the total pressure. since the partial pressure of each gas added together gives you the total pressure (raoult's law or something like that), the sum of all the partial pressures of the gases at equilibrium should equal 0.6atm. so the pressure at equilibrium will equal the pressure of C + B + A, or 2x + (0.5 - 2X) + (0.2 - x)

 

[Kneecoal]

ah. gracias.