# Gas Equilibria

## Homework Statement

The Equilibrium constant for A(g) -> 2B(g)
is 1x10^-2 at 1000k. Calculate the fraction on A which is dissociated at 1000k if the total pressure is
1 atm
10^-3 atm

## Homework Equations

PV=nRT
B^2 / A = Ke (1x10^-2)

## The Attempt at a Solution

for A PV=1x8.714x1000 = 8.714x10^3
for B PV=2x8.714x1000 = 17.428

All i can work out from this is that theres gunna be a 1:2 ratio? Im completely lost and my minds gone blank. Thanks in advance for the help

Related Biology and Chemistry Homework Help News on Phys.org
Borek
Mentor
Solve in terms of partial pressures. What is sum of pA and pB?

surely it would be pA+2pB=1atm ?
and im not very sure how to solve in terms of partial pressures

would i have
kp= pB^2 / pA
so 0.01 = pB^2 / pA

I've tried using a simultaneous equation with pA+2pB=1
and just end up with rubbish

Borek
Mentor
Why pA + 2 pB? Do you know definition of partial pressure?

because there's 2 moles of it? i thought that was right, my bad.

pA+pB=1atm that right?
would i be right to use a simlt equ then?

Borek
Mentor
2*yes.

ok using the equations i end up with the quadratic:
pB^2 + 0.01pB-0.01=0 so pB=0.095atm
so pA=0.905atm
and i can work out for the other atm

thanks