Equilibrium Constant

Question

A one-mole sample of NOBr was placed in a 10 L container at 25 °C, and the following reaction was allowed to come to equilibrium. 2 NOBr(g) ⇌ 2 NO(g) + Br₂(g) The equilibrium concentrations were found to be [NOBr] = 0.0838 M, [NO] = 0.0162 M and [Br₂] = 0.00810 M. Calculate the equilibrium constant, Kc, for the reaction. Note Kc is often called K.

Answer 1

HI Jordan,

The equilibrium constant, K_c is calculated by using the equilibrium concentrations and the mole ratios in teh balanced equation.

The equation says 2 NOBr ⇔ 2 NO + Br₂

The mole ratios will become exponents in your equilibrium expression.

To calculate K_c, the equation is K_c =[products]/[reactants]

For this specific equation, we would get the expression K_c = [Br₂] × [NO]²/[NOBr]²

Plugging in the equilibrium concentrations given we get K_c = (0.00810M) × (0.0162M)²/ (0.0838M)²

After calculation, we get 3.03 × 10^-4. The equilibrium constant has no units.