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1) Consider the reaction between sulfur dioxide and nitrogen dioxide: SO2(g) + N

ID: 824692 • Letter: 1

Question

1) Consider the reaction between sulfur dioxide and nitrogen dioxide: SO2(g) + NO2(g) <=====> SO3(g) + NO(g) Kc = 8.8 at 1000K

Given the following concentrations, predict in which direction the reaction will proceed:


a. [SO2 ] = 64.0 M, [NO2 ]=12.4 M, [SO3 ]=18.5 M, [NO ]=87.5 M
b. [SO2 ] = 1.73 M, [NO2 ]=0.581 M, [SO3 ]=4.89 M, [NO ]=158.2 M
c. PSO2 = 4.87 atm, PNO2 =4.87 atm, PSO3 =10.4 atm, PNO ]=10.4 atm


2) Consider the reaction:


HC2H3O2(aq) + H3O^+(aq) + C2H3O2^- (aq) Kc = 1.8e-5 at 25 deg C.

If a solution initially contains 0.210 M HC2H3O2, what is the equilibrium concentration of H3O^+ at 25 deg C.


3) Consider the following reaction:


Br2(g) + Cl2(g) <=====> 2BrCl(g) Kp= 1.11e-4 at 150K


A reaction mixture initially contains a Br2 partial pressure of 755 torr and a Cl2 partial pressure of 735 torr at 150K. Calculate the equilibrium partial pressure of BrCl.


Explanation / Answer

1.       For the reaction:

SO2 (g) +N02 (g) ? SO3 (g) +NO (g)

KC=8.8

a.       Here reaction quotient Q=[SO3][NO]/[SO2][NO2]

=18.5*87.5/64.0*12.4

=2.04

As Q< K, reaction will proceed in forward direction.

b.      Here reaction quotient Q=[SO3][NO]/[SO2][NO2]

=4.89*158.2/1.73*0.581

=769.6

As Q> K, reaction will proceed in backward direction.

c.       Now, Kp=Kc*(RT)?n

As ?n=0, for the above reaction

Kp=8.8

Here reaction quotient Q=PSO3*PNO/PSO2*PNO2

=10.4*10.4/4.87*4.87

=4.56

As Q< K, reaction will proceed in forward direction.

2.       For the reaction

HC2H3O2? H3O+ +C2H3O2-

                Initially:                                0.210M        0            0

                Finally:                  0.210-x          X           X

                KC=1.8*10-5

                KC=[H3O+][C2H3O2-]/[ HC2H3O2]

                1.8*10-5=X*X/(0.210-X)

                Solving, X=1.935*10-3

                So eqillibrium conc of H3O-=1.935*10-3M

3.       For the reaction

Br2(g) +   Cl2(g)? 2BrCl

                Initially:                                755             735         0

                Finally:                  755-X          735-X      2X

                KP=1.11*10-4

                KP=PBrCl2/PBr2*PCl2

                1.11*10-4=(2X)2/(755-X)(735-X)

                1.11*10-4(X2-1490X+554925)=4X2

                Solving, X=3.90

                So eqillibrium Pressure of BrCl=2X=2*3.90=7.80torr