At a temperature of 430 °C, the reaction H2(g) + I2(g) ⇌ 2 HI(g) has an equilibrium constant Kc = 54.3. Suppose that a mixture of 0.500 mol of H2(g) and 0.500 mol of I2(g) is placed into a 1.00-L stainless-steel flask at 430 °C. Calculate the concentration of HI(g) when equilibrium is reached. (LO 15.10) (a) 0.393 M (b) 0.107 M (c) 0.500 M (d) 0.786 M

Name: Chemistry
Author: McMurry
ISBN: 9781292336145

검증된 단계별 안내

Step 1: Write the balanced chemical equation for the reaction: \( \text{H}_2(g) + \text{I}_2(g) \rightleftharpoons 2 \text{HI}(g) \).

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

Step 3: Define the initial concentrations of the reactants. Since the volume of the flask is 1.00 L, the initial concentrations are \([\text{H}_2] = 0.500 \text{ M}\) and \([\text{I}_2] = 0.500 \text{ M}\).

Step 4: Assume that \( x \) moles of \( \text{HI} \) are formed at equilibrium. The change in concentration for \( \text{H}_2 \) and \( \text{I}_2 \) will be \(-x\), and for \( \text{HI} \) it will be \(+2x\).

Step 5: Substitute the equilibrium concentrations into the \( K_c \) expression: \( K_c = \frac{(2x)^2}{(0.500 - x)(0.500 - x)} = 54.3 \). Solve this equation for \( x \) to find the equilibrium concentration of \( \text{HI} \).

주요 개념

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

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 concentration. Understanding this concept is crucial for analyzing how concentrations change in response to initial conditions and how they relate to the equilibrium constant.

Equilibrium Constant (Kc)

The equilibrium constant (Kc) 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 the reaction H2(g) + I2(g) ⇌ 2 HI(g), Kc = [HI]^2 / ([H2][I2]). This constant provides insight into the extent of the reaction and is essential for calculating equilibrium concentrations from initial amounts.

ICE Table (Initial, Change, Equilibrium)

An ICE table is a tool used to organize the initial concentrations, the changes in concentrations as the reaction proceeds, and the equilibrium concentrations of reactants and products. By setting up an ICE table for the given reaction, one can systematically determine how the concentrations of H2, I2, and HI change from their initial values to equilibrium, facilitating the calculation of unknown concentrations using the equilibrium constant.