How Do You Determine Equilibrium Concentrations in a Chemical Reaction?

[erjkism]

[SOLVED] Chemistry equilibrium Question

Homework Statement

K=64. at 25 degrees celsius

N2(g) + 3H2(g) <--> 2NH3(g)

Molarity N2= .5M H2= 1.5M. what are the equilibrium concentrations?

i got the equilibrium table set up, and the K expression is
(2x)(2x)
k= ------------------------------
(.5-x)(1.5-3x)(1.5-3x)(1.5-3x)

how can i solve for x?

 

[Gannon]

I'm not sure if you raise the equilibrium concentrations to powers; if not, I have:

K = 2x / (0.5 - x)(1.5 - 3x)
K = 2x / (3x^2 - 3x + 0.75)
(3x^2 - 3x + 0.75)K = 2x
(3x^2 - 3x + 0.75)K -2x = 0
K3x^2 - K3x + K0.75 - 2x = 0
K = 64, so:

192x^2 - 190x + 48 = 0

Plug this into the quadratic equation, then substitute the answer for x for each concentration. For example, since the equilibrium concentration for NH2 is 2x, if x = 4, the equilibrium concentration would be 8M.

Just keep in mind that I'm not sure about raising the terms to stoichiometric powers in this kind of problem...

 

[chemisttree]

For equilibrium of a reaction of the type,

aA + bB +cC + ... \leftrightharpoons\ dD + eE + ...

the equilibrium expression is:

\frac{[D]^d[E]^e...}{[A]^a<b>^b[C]^c...}</b>

I'm not sure why you are using 'x' in your problem since it really isn't necessary.

 

[erjkism]

forget it i found out what to do