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Unformatted text preview: Elbel, Brittany – Homework 4 – Due: Feb 13 2006, noon – Inst: J A Holcombe 1 This print-out should have 14 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. The due time is Central time. 001 (part 1 of 1) 10 points For a reaction at equilibrium, which of the following is the best way to think about it? 1. The concentration of reactants and prod- ucts are not related. 2. The concentration of intermediates be- comes negligible. 3. forward rate = reverse rate correct 4. concentration of reactants = concentra- tion of products 5. The concentration of reactants becomes negligible. Explanation: In chemical systems, equilibrium is dy- namic and both foward and reverse processes continue to occur, but at the same rate. 002 (part 1 of 1) 10 points When the chemical reaction A + B * ) C + D is at equilibrium, 1. the sum of the concentrations of A and B equals the sum of the concentrations of C and D. 2. both the forward and reverse reactions have stopped. 3. the forward reaction has stopped. 4. all four concentrations are equal. 5. neither the forward nor the reverse reac- tions have stopped. correct 6. the reverse reaction has stopped. Explanation: Chemical equilibrium is dynamic equilib- rium, with both foward and reverse processes occuring at the same rate. 003 (part 1 of 1) 10 points What is the equilibrium expression for the following equation? A + 2B * ) 3C + D Assume that all species here are gases. 1. [C] 3 [D] [A][B] 2 correct 2. 2[A][B] 3[C][D] 3. 3[C][D] 2[A][B] 4. [A][B] 2 [C] 3 [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...
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- Spring '07
- Equilibrium, Elbel