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The initial concentrations or pressures of reactants and products are given for each of the following systems. Calculate the reaction quotient and determine the direction in which each system will proceed to reach equilibrium. (The system is considered in equilibrium if Kc and Qc are within 5% of each other.)

(a) 2 NH₃(g) equilibrium reaction arrow N₂(g) + 3 H₂(g) [NH₃]i = 0.540 M, [N₂]i = 0.165 M, [H₂]i = 0.110 M, Kc = 16 What is the reaction quotient?

(b) 2 NH₃(g) N₂(g) + 3 H₂(g) Pi(NH₃) = 1.95 atm, Pi(N₂) = 11.45 atm, Pi(H₂) = 11.45 atm, Kp = 4.4 ✕ 104 What is the reaction quotient?

(c) 2 SO₃(g) 2 SO₂(g) + O₂(g) [SO₃]i = 2.15 M, [SO₂]i = 2.15 M, [O₂]i = 2.15 M, Kc = 0.23 What is the reaction quotient?

(d) 2 SO₃(g) 2 SO₂(g) + O₂(g) Pi(SO₃) = 0.115 atm, Pi(SO₂) = 1.05 atm, Pi(O₂) = 1.20 atm, Kp = 7.8 atm What is the reaction quotient?

(e) 2 NO(g) + Cl₂(g) 2 NOCl(g) Pi(NO) = 1.30 atm, Pi(Cl₂) = 1.30 atm, Pi(NOCl) = 0 atm, Kp = 4.0 ✕ 103 What is the reaction quotient?

(f) N₂(g) + O₂(g) 2 NO(g) [N₂]i = 0.100 M, [O₂]i = 0.200 M, [NO]i = 1.00 M, Kc = 0.050

User Bidhan
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1 Answer

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(a) Initial concentrations yield \(Q_c = 0.185\), indicating the system will proceed forward to reach equilibrium.

(b) Initial pressures result in \(Q_p = 0.468\), suggesting the system will move forward to achieve equilibrium.

(c) For \(Q_c = 2.15 > K_c\), the system will shift in the reverse direction.

(d) Initial pressures yield \(Q_p = 84.15 > K_p\), causing the system to move backward toward equilibrium.

(e) Since the denominator is zero, the system is not at equilibrium, and the reaction will proceed until product concentrations are nonzero.

(f) Initial concentrations lead to \(Q_c = 50 > K_c\), indicating the system will shift backward to reach equilibrium.

(a) For the reaction \(2 \text{NH}_3(g) \rightleftharpoons \text{N}_2(g) + 3 \text{H}_2(g)\) with initial concentrations \([\text{NH}_3]_i = 0.540 \, \text{M}\), \([\text{N}_2]_i = 0.165 \, \text{M}\), \([\text{H}_2]_i = 0.110 \, \text{M}\), and \(K_c = 16\), the reaction quotient (\(Q_c\)) is calculated as follows:

\[ Q_c = \frac{[\text{N}_2][\text{H}_2]^3}{[\text{NH}_3]^2} \]

Substitute the given initial concentrations:

\[ Q_c = \frac{(0.165)(0.110)^3}{(0.540)^2} \approx 0.185 \]

Since \(Q_c\) is less than \(K_c\), the system will proceed in the forward direction to reach equilibrium.

(b) For the same reaction with initial pressures \(\text{Pi(NH}_3) = 1.95 \, \text{atm}\), \(\text{Pi(N}_2) = 11.45 \, \text{atm}\), \(\text{Pi(H}_2) = 11.45 \, \text{atm}\), and \(K_p = 4.4 \times 10^4\), the reaction quotient (\(Q_p\)) is calculated similarly:

\[ Q_p = \frac{\text{Pi(N}_2)\text{Pi(H}_2)^3}{(\text{Pi(NH}_3)^2} \approx 0.468 \]

Since \(Q_p\) is less than \(K_p\), the system will proceed in the forward direction to reach equilibrium.

(c) For the reaction \(2 \text{SO}_3(g) \rightleftharpoons 2 \text{SO}_2(g) + \text{O}_2(g)\) with initial concentrations \([\text{SO}_3]_i = 2.15 \, \text{M}\), \([\text{SO}_2]_i = 2.15 \, \text{M}\), \([\text{O}_2]_i = 2.15 \, \text{M}\), and \(K_c = 0.23\):

\[ Q_c = \frac{[\text{SO}_2]^2[\text{O}_2]}{[\text{SO}_3]^2} \]

Substitute the given initial concentrations:

\[ Q_c = \frac{(2.15)^2(2.15)}{(2.15)^2} = 2.15 \]

Since \(Q_c\) is greater than \(K_c\), the system will proceed in the reverse direction to reach equilibrium.

(d) For the same reaction with initial pressures \(\text{Pi(SO}_3) = 0.115 \, \text{atm}\), \(\text{Pi(SO}_2) = 1.05 \, \text{atm}\), \(\text{Pi(O}_2) = 1.20 \, \text{atm}\), and \(K_p = 7.8 \, \text{atm}\):

\[ Q_p = \frac{(\text{Pi(SO}_2)^2 \cdot \text{Pi(O}_2)}{\text{Pi(SO}_3)^2} \]

Substitute the given initial pressures:

\[ Q_p = \frac{(1.05)^2 \cdot 1.20}{(0.115)^2} \approx 84.15 \]

Since \(Q_p\) is greater than \(K_p\), the system will proceed in the reverse direction to reach equilibrium.

(e) For the reaction \(2 \text{NO(g)} + \text{Cl}_2(g) \rightleftharpoons 2 \text{NOCl(g)}\) with initial pressures \(\text{Pi(NO)} = 1.30 \, \text{atm}\), \(\text{Pi(Cl}_2) = 1.30 \, \text{atm}\), \(\text{Pi(NOCl)} = 0 \, \text{atm}\), and \(K_p = 4.0 \times 10^3\):

\[ Q_p = \frac{(\text{Pi(NO)})^2}{(\text{Pi(NOCl)})^2} \]

Substitute the given initial pressures:

\[ Q_p = \frac{(1.30)^2}{(0)^2} \]

Since the denominator is zero, the system is not at equilibrium, and the reaction will proceed until the concentrations of products are nonzero.

(f) For the reaction \( \text{N}_2(g) + \text{O}_2(g) \rightleftharpoons 2 \text{NO(g)} \) with initial concentrations \([\text{N}_2]_i = 0.100 \, \text{M}\), \([\text{O}_2]_i = 0.200 \, \text{M}\), \([\text{NO]_i} = 1.00 \, \text{M}\), and \(K_c = 0.050\):

\[ Q_c = \frac{[\text{NO}]^2}{[\text{N}_2][\text{O}_2]} \]

Substitute the given initial concentrations:

\[ Q_c = \frac{(1.00)^2}{(0.100)(0.200)} = 50 \]

Since \(Q_c\) is greater than \(K_c\), the system will proceed in the reverse direction to reach equilibrium.

User Subhajit
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