HW4-ex2

# HW4-ex2 - dsj294 hw04 Holcombe (53570) This print-out...

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dsj294 – hw04 – Holcombe – (53570) 1 This print-out should have 25 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. 001 10.0 points When a reaction reaches equilibrium, 1. the Forward and reverse reaction rates are equal. correct 2. all reaction stops. 3. the rate oF the reverse reaction is zero. 4. the rate oF the Forward reaction and the rate oF the reverse reaction are equal to zero. 5. the rate oF the Forward reaction is zero. Explanation: Chemical equilibrium is a dynamic equilib- rium in which both the Forward and reverse reaction are continually going. There is a con- stant turn over oF reactant to product and vice versa. By defnition the two rates must equal one another in order For the concentrations oF all species to remain constant with time. 002 10.0 points Write the equilibrium expression For the reac- tion 2 NO(g) + O 2 (g) 2 NO 2 (g) 1. K = P 2 NO P O 2 P 2 NO 2 2. K = P 2 NO 2 P 2 NO P O 2 correct 3. K = 2 P NO 2 2 P NO P O 2 4. K = P NO P NO 2 P O 2 5. K = P NO 2 P 2 NO P O 2 Explanation: Since this is a gas phase reaction, K is the ratio oF the partial equilibrium pressures oF the products to the partial equilibrium pres- sures oF the reactants. 003 10.0 points ±or the heterogeneous reaction 2 MnO 2 (s) 2 MnO(s) + O 2 (g) , the equilibrium constant expression For K c is which oF the Following? 1. K c = [MnO] [O 2 ] [MnO 2 ] 2. K c = [MnO 2 ] [MnO] [O 2 ] 3. K c = 1 [O 2 ] 4. K c = [O 2 ] correct 5. K c = k [MnO 2 ] Explanation: ±or heterogeneous reactions, only gaseous reactants and species are taken into considera- tion when writing K c expressions. ThereFore, K c = [O 2 ]. 004 10.0 points Given the Following equilibria and equilibrium constants K 1 CO(g) + H 2 O(g) CO 2 (g) + H 2 (g) K 2 CH 4 (g) + H 2 O(g) CO(g) + 3 H 2 (g) K 3 CH 4 (g) + 2 H 2 O(g) CO 2 (g) + 4 H 2 (g) The correct expression For K 3 in terms oF K 1 and K 2 is 1. K 3 = K 1 K 2 2. K 3 = K 1 + K 2 3. K 3 = K 1 K 2 4. Cannot be determined From this inForma- tion. 5. K 3 = K 1 K 2 correct Explanation:

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dsj294 – hw04 – Holcombe – (53570) 2 CO(g) + H 2 O(g) CO 2 (g) + H 2 (g) K 1 = [CO 2 ][H 2 ] [CO][H 2 O] CH 4 (g) + H 2 O(g) CO(g) + 3 H 2 (g) K 2 = [CO][H 2 ] 3 [CH 4 ][H 2 O] Adding (1) and (2), CO(g) + H 2 O(g) + CH 4 (g) + H 2 O(g) CO 2 (g) + H 2 (g) + CO(g) + 3 H 2 (g) CH 4 (g) + 2 H 2 O(g) CO 2 (g) + 4 H 2 (g) K 3 = [CO 2 ][H 2 ] 4 [CH 4 ][H 2 O] 2 K 1 K 2 = p [CO 2 ][H 2 ] [CO][H 2 O] Pp [CO][H 2 ] 3 [CH 4 ][H 2 O] P = [CO 2 ][H 2 ] 4 [CH 4 ][H 2 O] 2 = K 3 005 10.0 points The equilibrium constant for the reaction HNO 2 (aq) + H 2 O( ) NO 2 (aq) + H 3 O + (aq) is 4 . 3 × 10 4 at 25 C. Will nitrous acid spon- taneously dissociate when [HNO 2 (aq)] = 0.15 M and [NO 2 (aq)] = [H 3 O + (aq)] = 1 . 0 × 10 2 M? 1.
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## This note was uploaded on 02/26/2009 for the course CH 58734 taught by Professor Bronzewook during the Spring '07 term at UT Chattanooga.

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HW4-ex2 - dsj294 hw04 Holcombe (53570) This print-out...

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