A sample of nitrosyl bromide (NOBr) decomposes according to the equation 2 NOBr(g) ⇌ 2 NO(g) + Br2(g). An equilibrium mixture in a 5.00-L vessel at 100 _x001F_C contains 3.22 g of NOBr, 3.08 g of NO, and 4.19 g of Br2. (a) Calculate Kc.

Verified step by step guidance

First, convert the masses of NOBr, NO, and Br2 to moles using their respective molar masses. Use the formula: \( \text{moles} = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}} \).

Next, calculate the concentrations of each species in the equilibrium mixture. Since the volume of the vessel is 5.00 L, use the formula: \( \text{concentration (M)} = \frac{\text{moles}}{\text{volume (L)}} \).

Write the expression for the equilibrium constant \( K_c \) for the reaction: \( K_c = \frac{[\text{NO}]^2[\text{Br}_2]}{[\text{NOBr}]^2} \).

Substitute the concentrations of NO, Br2, and NOBr into the \( K_c \) expression. Ensure that the concentrations are raised to the power of their stoichiometric coefficients.

Finally, solve the expression to find the value of \( K_c \). This will give you the equilibrium constant for the reaction at the given temperature.

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 concentrations are in mol/L. A larger Kc indicates a greater concentration of products at equilibrium, while a smaller Kc suggests that reactants are favored.

Molar Mass and Conversion to Molarity

To calculate Kc, it is essential to convert the mass of each substance into moles using their molar masses. Molarity (M) is then determined by dividing the number of moles by the volume of the solution in liters. This step is crucial because Kc is based on concentrations, and accurate conversion ensures correct equilibrium calculations.

Stoichiometry of the Reaction

Understanding the stoichiometry of the reaction is vital for determining the correct coefficients when calculating Kc. In the given reaction, 2 moles of NOBr decompose to produce 2 moles of NO and 1 mole of Br2. The stoichiometric coefficients directly influence the equilibrium expression, as they dictate how the concentrations of each species are related in the Kc calculation.

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Textbook Question

When 2.00 mol of SO₂Cl₂ is placed in a 2.00-L flask at 303 K, 56% of the SO₂Cl₂ decomposes to SO₂ and Cl₂: SO₂Cl₂(g) ⇌ SO₂(g) + Cl₂(g) (a) Calculate K_c for this reaction at this temperature.

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Textbook Question

When 2.00 mol of SO₂Cl₂ is placed in a 2.00-L flask at 303 K, 56% of the SO₂Cl₂ decomposes to SO₂ and Cl₂: SO₂Cl₂(g) ⇌ SO₂(g) + Cl₂(g) (c) According to Le Châtelier's principle, would the percent of SO₂Cl₂ that decomposes increase, decrease or stay the same if the mixture were transferred to a 15.00-L vessel?

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Textbook Question

A sample of nitrosyl bromide (NOBr) decomposes according to the equation 2 NOBr(𝑔) ⇌ 2 NO(𝑔) + Br₂(𝑔) An equilibrium mixture in a 5.00-L vessel at 100°C contains 3.22 g of NOBr, 3.08 g of NO, and 4.19 g of Br₂. (b) What is the total pressure exerted by the mixture of gases?

Textbook Question

A sample of nitrosyl bromide (NOBr) decomposes according to the equation 2 NOBr(g) ⇌ 2 NO(g) + Br₂(g) An equilibrium mixture in a 5.00-L vessel at 100°C contains 3.22 g of NOBr, 3.08 g of NO, and 4.19 g of Br₂. (c) What was the mass of the original sample of NOBr?