In: Chemistry
At equilibrium, the concentrations in this system were found to be
[N2]=[O2]=0.200 M and [NO]=0.500 M.
N2(g)+O2(g)<----->2NO(g)
If more NO is added, bringing its concentration to 0.800 M, what will the final concentration of NO be after equilibrium is re-established?
____________M
the first thing to do is to calculate the equilibrium constant of concentration Kc so:
N2(g)+O2(g)<----->2NO(g).
the equilibrium constant is the relationship between products and reactants so:
Kc = [NO]2 / [N2] [O2]
calculate Kc with the given numbers:
Kc = [0.5]2 / [0.2] [0.2] = 6.25
now analyze the equilibrium with the concentration of NO = 0.8 M, according to lecheteliers principle the equilibrium will shift to the left because you have more of product than the original case
N2(g) + O2(g)<-----> 2NO(g).
I........0.2...............................0.2..........................0.8
C.....+x................................+x............................-x
E......0.2+x...........................0.2+x....................0.8-2x
the equilibrium constant is expressed as:
(0.8 - 2x)2 / (0.2+x)(0.2+x) = 6.25
solve this equation to get the value of x, i am using a spreadsheet so x is 0.0666 M
the concentration of NO is
0.8 - 2 * 0.0666 = 0.666 M
*hope it helps =)