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° CO 2 ( g ) + H 2 ( g ) CO( g ) + H 2 O( g ) [CO 2 ] = 0.0870 M , ° Be sure to

ID: 496202 • Letter: #

Question

°

CO2(g) + H2(g) CO(g) + H2O(g)

[CO2] = 0.0870 M,

°

Be sure to answer all parts.

Consider the following equilibrium process at 686

°

C:

CO2(g) + H2(g) CO(g) + H2O(g)


The equilibrium concentrations of the reacting species are [CO] = 0.0580 M, [H2] = 0.0420 M,

[CO2] = 0.0870 M,

and [H2O] = 0.0390 M.

(a) Calculate Kc for the reaction at 686

°

C.



(b) If we add CO2 to increase its concentration to 0.520 mol / L, what will the concentrations of all the gases be when equilibrium is reestablished?

CO2:

M

H2:

M

CO:

M

H2O:

M X

Explanation / Answer

A.) Kc = [CO]{H2O] / [CO2][H2]

Kc = 0.058x0.039 / 0.087x0.042

Kc = 0.62

B.) asssume 1L vessel

no.of moles of co2 added = 0.52

no.of moles of H2 be x

assuming hydrogen as a limiting reagent then

at equilibrium ,

no.of moles of co2 = (0.52 - x )

no.of moles of H2 = 0+0.042 =0.042

no.of moles of CO = 0.058+x

no.of moles of H2O = 0.039+x

the Kc value remains constant as there is no change in temperature.

0.62 = (0.058+x)*(0.039+x)/(0.52 -x)*(0.042)

x=0.18

concentration of CO2=0.34

conc of H2 =0.042

conc of CO = 0.238

conc of H2O = 0.219