HW3n_pdf - leazenby(jl35875 – Homework 3 – Sutcliffe...

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Unformatted text preview: leazenby (jl35875) – Homework 3 – Sutcliffe – (52440) 1 This print-out should have 21 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0 points When the chemical reaction A + B ⇀ ↽ C + D is at equilibrium, 1. the reverse reaction has stopped. 2. neither the forward nor the reverse reac- tions have stopped. correct 3. the forward reaction has stopped. 4. the sum of the concentrations of A and B equals the sum of the concentrations of C and D. 5. both the forward and reverse reactions have stopped. 6. all four concentrations are equal. Explanation: Chemical equilibrium is dynamic equilib- rium, with both foward and reverse processes occuring at the same rate. 002 10.0 points What is the equilibrium expression for the following equation? Assume that all species here are gases. A + 3 B ⇀ ↽ 2 C + D 1. 2 [C] [D] 3 [A] [B] 2. [A] [B] 3 [C] 2 [D] 3. [C] 2 [D] [A] [B] 3 correct 4. 3 [A] [B] 2 [C] [D] Explanation: Equilibrium expressions are written with the products (raised to the powers of their co- efficients) in the numerator and the reactants (raised to the powers of their coefficients) in the denominator. 003 10.0 points What is the form of the equilibrium constant for the process PbO(s) + CO 2 (g) ⇀ ↽ PbCO 3 (s) ? P species means the pressure of species. 1. K p = P PbCO 3 P CO 2 2. K p = [PbCO 3 ] [PbO] P CO 2 3. K p = 1 P CO 2 correct 4. No other choice is correct. 5. K c = [PbCO 3 ] 2 [CO 2 ] [PbO] Explanation: Solids are not included in the K expression. 004 10.0 points Consider the following reactions at 25 ◦ C: reaction K c 2 NO(g) ⇀ ↽ N 2 (g) + O 2 (g) 1 × 10 30 2 H 2 O(g) ⇀ ↽ 2 H 2 (g) + O 2 (g) 5 × 10 − 82 2 CO(g) + O 2 (g) ⇀ ↽ 2 CO 2 (g) 3 × 10 91 Which compound is most likely to dissociate and give O 2 (g) at 25 ◦ C? 1. H 2 O 2. NO correct 3. CO 4. CO 2 Explanation: Only two are dissociation reactions: disso- ciation of NO and dissociation of H 2 O. K c is greater for dissociation of NO. leazenby (jl35875) – Homework 3 – Sutcliffe – (52440) 2 005 10.0 points Note in this question it doesn’t matter if it refers to K c or K p as long as you are consistent. The equilibrium constant for the reaction 4 NH 3 (g) + 5 O 2 (g) → 4 NO(g) + 6 H 2 O(g) is K . Calculate the equilibrium constant for the reaction 2 NO(g) + 3 H 2 O(g) → 2 NH 3 (g) + 5 2 O 2 (g) . 1.- 2 K 2.- K 3. 1 √ K correct 4.- K 2 5. 1 K Explanation: 006 10.0 points Note in this question it doesn’t matter if it refers to K c or K p as long as you are consistent. If the equilibrium constant for the reaction Ni(s) + 4 CO(g) → Ni(CO) 4 (g) is 2.72 at a certain temperature, what is the equilibrium constant for the reaction Ni(CO) 4 (g) → Ni(s) + 4 CO(g) at the same temperature?...
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HW3n_pdf - leazenby(jl35875 – Homework 3 – Sutcliffe...

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