balance: Al(s)+H2O(g)--->Al2O3(s)+H2(g)
what is the correct equilibrium expression?
The correct equilibrium expression for the given balanced equation is:
\[ K = \frac{{[Al_2O_3][H_2]}}{{[Al][H_2O]}} \]
To determine the correct equilibrium expression for the given balanced chemical equation, you should first identify the products and reactants in the equation:
Reactants: Al(s), H2O(g)
Products: Al2O3(s), H2(g)
The equilibrium expression is typically written in terms of the concentration of each species involved in the reaction. In this case, since Al(s) and Al2O3(s) are solids, they are not included in the equilibrium expression because their concentration remains constant.
The equilibrium expression is written as the ratio of the concentrations of the products to the concentrations of the reactants, with the concentrations raised to the power of their respective stoichiometric coefficients as shown in the balanced equation.
For this reaction, the equilibrium expression would be:
Kc = [H2(g)] / [H2O(g)]
Note that the stoichiometric coefficients from the balanced equation (1 for H2(g) and H2O(g)) are used in forming the expression. The square brackets indicate the concentration of each species.
It is important to note that for gaseous components, the equilibrium expression can also be written in terms of their partial pressures (Kp) instead of concentrations. However, since the equation is given in terms of concentrations, we use Kc in this case.