Worksheet 2 Equilibrium Expressions and Calculations Answers
Introduction
Equilibrium expressions and calculations are an essential part of understanding chemical reactions and their dynamics. In Worksheet 2, you were introduced to various equilibrium problems and asked to calculate equilibrium constants, concentrations, and other related values. In this article, we will provide you with the answers to Worksheet 2, helping you to check your work and enhance your understanding of equilibrium concepts.
Question 1
The first question in Worksheet 2 asks you to write the equilibrium expression for the reaction:
N2(g) + 3H2(g) ⇌ 2NH3(g)
Answer: The equilibrium expression for this reaction is:
Kc = [NH3]^2 / ([N2] * [H2]^3)
Question 2
The second question involves calculating the equilibrium constant for the reaction:
2SO2(g) + O2(g) ⇌ 2SO3(g)
Given the following equilibrium concentrations:
[SO2] = 0.5 M
[O2] = 0.25 M
[SO3] = 0.75 M
Answer: To calculate the equilibrium constant, plug the concentrations into the equilibrium expression:
Kc = [SO3]^2 / ([SO2]^2 * [O2])
Kc = (0.75^2) / ((0.5^2) * 0.25) = 9
Question 3
Question 3 asks you to determine the equilibrium concentration of a reactant given the equilibrium constant and the concentrations of the other species. The reaction is:
2H2(g) + S2(g) ⇌ 2H2S(g)
Given the following equilibrium concentrations:
[H2] = 0.2 M
[H2S] = 0.6 M
Kc = 2.5
Answer: Let x be the concentration of S2 at equilibrium. The equilibrium expression is:
Kc = [H2S]^2 / ([H2]^2 * [S2])
Substituting the given values:
2.5 = (0.6^2) / ((0.2^2) * x)
Solving for x, we find that [S2] = 0.144 M
Question 4
Question 4 deals with calculating the equilibrium constant using partial pressures. The reaction is:
2NO2(g) ⇌ N2O4(g)
Given the following equilibrium pressures:
P(NO2) = 0.8 atm
P(N2O4) = 0.5 atm
Answer: The equilibrium constant can be calculated using the partial pressures:
Kp = (P(N2O4)) / (P(NO2))^2
Kp = 0.5 / (0.8)^2 = 0.78125
Question 5
Question 5 requires you to calculate the equilibrium concentration of a product given the equilibrium constant and the concentrations of the reactants. The reaction is:
2CH3OH(g) ⇌ CO2(g) + 3H2(g)
Given the following equilibrium concentrations:
[CH3OH] = 0.2 M
[CO2] = 0.1 M
Kc = 0.5
Answer: Let x be the concentration of H2 at equilibrium. The equilibrium expression is:
Kc = ([CO2] * [H2]^3) / ([CH3OH]^2)
Substituting the given values:
0.5 = (0.1 * x^3) / (0.2^2)
Solving for x, we find that [H2] = 0.158 M
Question 6
Question 6 involves calculating the equilibrium constant for the reaction:
PCl5(g) ⇌ PCl3(g) + Cl2(g)
Given the following equilibrium concentrations:
[PCl5] = 0.1 M
[PCl3] = 0.2 M
[Cl2] = 0.3 M
Answer: To calculate the equilibrium constant, divide the product concentrations by the reactant concentration:
Kc = ([PCl3] * [Cl2]) / [PCl5]
Kc = (0.2 * 0.3) / 0.1 = 0.6
Question 7
Question 7 asks you to find the equilibrium constant for the reaction:
N2(g) + 3H2(g) ⇌ 2NH3(g)
Given the following equilibrium concentrations:
[N2] = 0.4 M
[H2] = 0.2 M
[NH3] = 0.6 M
Answer: The equilibrium constant can be calculated by dividing the product concentration by the reactant concentrations:
Kc = [NH3]^2 / ([N2] * [H2]^3)
Kc = (0.6^2) / (0.4 * (0.2^3)) = 75
Question 8
Question 8 involves calculating the equilibrium concentration of a reactant given the equilibrium constant and the concentrations of the other species. The reaction is:
2H2O(g) ⇌ 2H2(g) + O2(g)
Given the following equilibrium concentrations:
[H2] = 0.1 M
[O2] = 0.2 M
Kc = 0.5
Answer: Let x be the concentration of H2O at equilibrium. The equilibrium expression is:
Kc = ([H2]^2 * [O2]) / [H2O]^2
Substituting the given values:
0.5 = (0.1^2 * 0.2) / x^2
Solving for x, we find that [H2O] = 0.1 M
Question 9
Question 9 deals with calculating the equilibrium constant using partial pressures. The reaction is:
2SO2(g) + O2(g) ⇌ 2SO3(g)
Given the following equilibrium pressures:
P(SO2) = 0.4 atm
P(O2) = 0.3 atm
P(SO3) = 0.6 atm
Answer: The equilibrium constant can be calculated using the partial pressures:
Kp = (P(SO3))^2 / (P(SO2))^2 * P(O2)
Kp = (0.6)^2 / (0.4)^2 * 0.3 = 0.675
Question 10
Question 10 requires you to calculate the equilibrium concentration of a product given the equilibrium constant and the concentrations of the reactants. The reaction is:
2NH3(g) ⇌ N2(g) + 3H2(g)
Given the following equilibrium concentrations:
[NH3] = 0.2 M
[N2] = 0.4 M
[H2] = 0.3 M
Answer: Let x be the concentration of NH3 at equilibrium. The equilibrium expression is:
Kc = ([N2] * [H2]^3) / [NH3]^2
Substituting the given values:
Kc = (0.4 * (0.3^3)) / (x^2)
Solving for x, we find that [NH3] = 0.358 M
Conclusion
Equilibrium expressions and calculations play a crucial role in understanding chemical reactions and their behavior. By practicing with Worksheet 2 and checking your answers using this article, you can enhance your understanding of equilibrium concepts and improve your problem-solving skills. Remember to carefully analyze the given information and apply the appropriate equilibrium expressions to solve each problem. With practice, you'll become more proficient in equilibrium calculations and be better equipped to tackle more complex problems in the future.