Question

The elementary reaction 2H2O(l) <--> 2H2(g) + O2 (g) has the partial pressures of H2O, H2, and O2 reach 0.0500 atm, 0.00200 atm, and 0.00450 atm respectively. What is the value of the equilibrium constant at this temperature?

Answer 1

Using the definition of the equilibrium constant, we find that `K = 7.2 xx 10^-6`

Explanation:

The equilibrium constant, K, for any reaction is defined as the concentrations of the products raised by their coefficients divided by the concentrations of the reactants raised by their coefficients. In this case, the concentrations are given as partial pressures.

`"In other words, the equilibrium constant K can be defined for any reaction"` `wA + xB -> yC + zD` `"as K" = ([C]^y xx [D]^z)/([A]^w xx [B]^x)`

The reaction given is as follows:

`2H_2O rightleftharpoons 2H_2 + O_2`

`"Using the definition of K from before, we can now define K as"`
`K = ([O_2] xx [H_2]^2)/([H_2O]^2)`

When we plug in the values for the given pressures, we get

`K = ([.0045] xx [.002]^2)/([.05]^2) = 7.2 xx 10^-6`