A sample of HI 19.30 * 10^-3 mol^2 was placed in an empty 2.00-L container at 1000 K. After equilibrium was reached, the concentration of I2 was 6.29 * 10^-4 M. Calculate the value of Kc at 1000 K for the reaction H2(g) + I2(g) ⇌ 2 HI(g).

Name: Chemistry
Author: McMurry
ISBN: 9781292336145

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Identify the balanced chemical equation for the reaction: \( \text{H}_2(g) + \text{I}_2(g) \rightleftharpoons 2 \text{HI}(g) \).

Write the expression for the equilibrium constant \( K_c \) for the reaction: \( K_c = \frac{[\text{HI}]^2}{[\text{H}_2][\text{I}_2]} \).

Determine the initial concentration of HI by dividing the initial moles by the volume of the container: \( \frac{19.30 \times 10^{-3} \text{ mol}}{2.00 \text{ L}} \).

Use the stoichiometry of the reaction to express the changes in concentration of \( \text{H}_2 \), \( \text{I}_2 \), and \( \text{HI} \) in terms of a variable \( x \), where \( x \) is the change in concentration of \( \text{I}_2 \) at equilibrium.

Substitute the equilibrium concentrations into the \( K_c \) expression and solve for \( K_c \).

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Equilibrium Constant (Kc)

The equilibrium constant, Kc, quantifies the ratio of the concentrations of products to reactants at equilibrium for a given reaction at a specific temperature. It is calculated using the formula Kc = [products]^coefficients / [reactants]^coefficients. A larger Kc value indicates a greater concentration of products at equilibrium, while a smaller Kc suggests a higher concentration of reactants.

Concentration and Molarity

Concentration refers to the amount of a substance in a given volume of solution, commonly expressed in molarity (M), which is moles of solute per liter of solution. In this problem, the concentration of I2 is given as 6.29 * 10^-4 M, indicating the number of moles of I2 present in one liter of the solution. Understanding how to convert moles to molarity is crucial for calculating Kc.

Stoichiometry of the Reaction

Stoichiometry involves the quantitative relationships between the reactants and products in a chemical reaction. For the reaction H2(g) + I2(g) ⇌ 2 HI(g), the stoichiometric coefficients indicate that one mole of H2 reacts with one mole of I2 to produce two moles of HI. This relationship is essential for determining the concentrations of all species at equilibrium, which are needed to calculate Kc.