At a certain temperature,K_c equals 1.4 × 10² for the reaction:
2 CO(g) + O₂(g) ⇌ 2 CO₂(g) .
If a 3.00-L flask contains 0.400 mol of CO₂ and 0.100 mol of O₂ at equilibrium,how many moles of CO are also present in the flask?

Question

Quizplus · Accepted Answer

The equilibrium constant, K, can be found by plugging in the concentrations of the reactants and products at equilibrium into the equilibrium expression.

K = [COS]/[CO][O2] = 1.4 × 10^12

Let x be the amount of CO at equilibrium. Then, the change in concentration of each species is:

[COS]: -2x mol
[CO]: +2x mol
[O2]: -x mol

At equilibrium,

[COS] = 0.400 - 2x
[O2] = 0.100 - x
[CO] = x

Using the equilibrium constant expression, we can set up an equation:

1.4 × 10^12 = ([COS]/[CO][O2])eq = ((0.400 - 2x)/x(0.100 - x))eq

Solving for x, we get x = 0.185 mol, which is the amount of CO at equilibrium.

Therefore, the answer is B) 0.185 mol.

At a Certain Temperature,Kc Equals 1

At a Certain Temperature,K_c Equals 1