For each of the following equilibria, write the equilibrium constant expression for Kc. (a) CH4(g) + H2O(g) ⇌ CO(g) + 3 H2(g) (b) 3 F2(g) + Cl2(g) ⇌ 2 ClF3(g) (c) H2(g) + F2(g) ⇌ 2 HF(g)

Verified step by step guidance

Step 1: Understand the concept of equilibrium constant (Kc). The equilibrium constant expression for a reaction is derived from the balanced chemical equation and is a ratio of the concentrations of products to reactants, each raised to the power of their respective coefficients in the balanced equation.

Step 2: For reaction (a) CH4(g) + H2O(g) ⇌ CO(g) + 3 H2(g), write the equilibrium constant expression Kc = [CO][H2]^3 / [CH4][H2O].

Step 3: For reaction (b) 3 F2(g) + Cl2(g) ⇌ 2 ClF3(g), write the equilibrium constant expression Kc = [ClF3]^2 / [F2]^3[Cl2].

Step 4: For reaction (c) H2(g) + F2(g) ⇌ 2 HF(g), write the equilibrium constant expression Kc = [HF]^2 / [H2][F2].

Step 5: Remember that the concentrations are typically expressed in molarity (moles per liter) and that the equilibrium constant is dimensionless.

Key Concepts

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

Equilibrium Constant (Kc)

The equilibrium constant, Kc, is a numerical value that expresses the ratio of the concentrations of products to reactants at equilibrium for a given chemical reaction. It is calculated using the formula Kc = [products]^[coefficients] / [reactants]^[coefficients], where the brackets denote molarity and the coefficients are the stoichiometric coefficients from the balanced equation.

Chemical Equilibrium

Chemical equilibrium occurs when the rates of the forward and reverse reactions are equal, resulting in constant concentrations of reactants and products over time. At this point, the system is in a state of balance, and the concentrations of all species remain unchanged unless disturbed by external factors, such as changes in temperature or pressure.

Stoichiometry in Equilibrium Expressions

Stoichiometry refers to the relationship between the quantities of reactants and products in a chemical reaction. In equilibrium expressions, the coefficients from the balanced chemical equation are used as exponents in the Kc expression, reflecting the proportionality of the concentrations of each species involved in the reaction at equilibrium.

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Equilibrium Constant Expressions

Related Practice

Textbook Question

The following pictures represent the initial and equilibrium states for the exothermic reaction of solid A (red) with gas- eous B2 (blue) to give gaseous AB. (a) Write a balanced chemical equation for the reaction.

Textbook Question

Identify the true statement about the rate of the forward and reverse reaction once a reaction has reached equilibrium. (a) The rate of the forward reaction and the reverse reaction is zero. (b) The rate of the forward reaction is greater than the rate of the reverse reaction. (c) The rate of the reverse reaction is greater than the rate of the forward reaction. (d) The rate of the forward reaction is equal to the rate of the reverse reaction.

Textbook Question

For each of the equilibria in Problem 15.56, write the equi-librium constant expression for Kp and give the equation that relates Kp and Kc. (a)