Consider the equilibrium: 2NO (g) + O2 (g) 2NO2 (g) At 100 degrees Celsius the equilibrium concentrations for this system are: [NO]=0.52 M [O2]=0.24 M [NO2]=0.18 M Write the expression for Kp and calculate its value at this temperature. (I think I should use the Kp=K(RT)^delta n formula, but I don't know how to find K from concentrations...)

Question

Consider the equilibrium: 2NO (g) + O2 (g) <---> 2NO2 (g)
At 100 degrees Celsius the equilibrium concentrations for this system are:

[NO]=0.52 M  [O2]=0.24 M  [NO2]=0.18 M

Write the expression for Kp and calculate its value at this temperature. 

(I think I should use the Kp=K(RT)^delta n formula, but I don't know how to find K from concentrations...)

nali · Answer

you could use the concentration that are given since they are at equilibrium but include the coefficients as the exponents on these concentrations in this format: 

k= [NO2]^2 / ([O2]X[NO]^2)