Question

What is the correct form of the equilibrium constant for the reaction of hydrogen and oxygen to form water? The equation is: 2H 2( g) + O 2( g) ⇌ H 2O( g)

Answer 1

The equilibrium constant is given by the ratio between the products and the reactants, where their stoichiometric numbers are exponents.

$K=\frac{\lbrack H_2O\rbrack^2^{}^{}}{\lbrack H_2\rbrack^2\lbrack O_2\rbrack}$

Observe that the molecule H2O must have a coefficient of 2 in order to balance the equation.

• [H2O] is the equilibrium concentration of the product (water).

,

• [H2} is the equilibrium concentration of the hydrogen molecule.

,

• [O2] is the equilibrium concentration of the oxygen molecule.