What is the equilibrium expression for the reaction of iron metal with water vapor? (LO 15.2 and 15.6) 2 Fe(s) + 3 H2O(g) ⇌ Fe2O3(s) + 3 H2(g)

Verified step by step guidance

Identify the phases of each component in the reaction: Fe(s), H2O(g), Fe2O3(s), and H2(g).

Recall that the equilibrium expression, K, is written in terms of the concentrations of the gaseous and aqueous species only.

Write the general form of the equilibrium constant expression: K = [products]^coefficients / [reactants]^coefficients.

Since Fe(s) and Fe2O3(s) are solids, they do not appear in the equilibrium expression.

Write the equilibrium expression for the reaction: K = [H2]^3 / [H2O]^3.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Chemical Equilibrium

Chemical equilibrium occurs when the rates of the forward and reverse reactions are equal, resulting in constant concentrations of reactants and products. In this state, the system is dynamic, meaning that reactions continue to occur, but there is no net change in the concentrations of substances involved.

Equilibrium Constant (K)

The equilibrium constant (K) is a numerical value that expresses the ratio of the concentrations of products to reactants at equilibrium, each raised to the power of their coefficients in the balanced equation. For gaseous and aqueous species, K is calculated using molar concentrations, while solids and liquids are not included in the expression.

Phase of Reactants and Products

In equilibrium expressions, only gases and aqueous solutions are included, while solids and pure liquids are omitted. This is because the concentration of solids and liquids does not change during the reaction, making their inclusion unnecessary for calculating the equilibrium constant.

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Textbook Question

The reaction A21g2 + B21g2 ∆ 2 AB1g2 has an equilib- rium constant Kc = 9. The following figure represents areaction mixture that contains A2 molecules (red), B2 mol- ecules (blue), and AB molecules. What statement about the mixture is true? (LO 15.5)

(a) The mixture is at equilibrium, and there will be no net shift in reaction direction.(b) The reaction will shift toward the reactants to reach equilibrium.(c) The reaction will shift toward the products to reach equilibrium.(d) More information is needed to answer this question.

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