SUPPL INSTR FOR CH 302 (GE 206E) - HW3SOL

# SUPPL INSTR FOR CH 302 (GE 206E) - HW3SOL - Moore, Robert...

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Moore, Robert – Homework 3 – Due: Feb 18 2007, midnight – Inst: McCord 1 This print-out should have 16 questions. Multiple-choice questions may continue on the next column or page – fnd all choices be±ore answering. The due time is Central time. 001 (part 1 o± 1) 10 points An equilibrium in which processes occur con- tinuously, with NO NET change, is called 1. heterogeneous equilibrium. 2. static equilibrium. 3. dynamic equilibrium. correct 4. homogeneous equilibrium. Explanation: For a system at dynamic equilibrium, al- though the concentrations o± the components do not change, the processes continue to oc- cur in the ±oward and reverse directions at the same rate. 002 (part 1 o± 1) 10 points Explain why equilibium constants are dimen- sionless. 1. Every concentration or pressure that en- ters into K c or K p is really divided by the cor- responding concentration or pressure o± the substance in its standard state. correct 2. They are dimensionless because the pres- sures or concentrations we put in are all ±or the substances in their standard states. 3. They are not really dimensionless but we must treat them as such in order to be able to take ln K in the expression Δ G 0 = - R T ln K . 4. They are dimensionless because concen- trations and pressures have no units. 5. The statement is not true. Equilibrium constants have units that involve some multi- ple o± atmospheres or moles per liter. Explanation: The amount o± each component is in terms o± activity, which is the measured amount (concentration, pressure) divided by the amount o± that component in its standard state in that unit. The units in the numera- tor and denominator are identical and cancel out. 003 (part 1 o± 1) 10 points Consider the reaction 2HgO(s) * ) 2Hg( ) + O 2 (g) . What is the ±orm o± the equilibrium constant K c ±or the reaction? 1. K c = [Hg] 2 [O 2 ] [HgO] 2 2. None o± the other answers is correct. 3. K c = [O 2 ] [HgO] 2 4. K c = [O 2 ] correct 5. K c = [Hg] 2 [O 2 ] Explanation: Solids and liquids are not included in the K expression. 004 (part 1 o± 1) 10 points The expression ±or K c ±or the reaction at equi- librium is 4 NH 3 (g) + 5 O 2 (g) * ) 4 NO(g) + 6 H 2 O(g) 1. [NH

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## This note was uploaded on 09/28/2009 for the course GE 206E taught by Professor staff during the Spring '09 term at University of Texas.

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SUPPL INSTR FOR CH 302 (GE 206E) - HW3SOL - Moore, Robert...

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