Ask a question

How do I solve this AP Chemistry problem on the reaction C (s)+H2O(g)==>CO (g)+H2 (g)?

CO (g) + H2(g) <--> C(s) + H2O (g) ∆H˚ = -131 kJ

A rigid container holds a mixture of graphite pellets (C(s)), H2O(g), CO(g), and H2(g) at equilibrium. State whether the number of moles of CO (g) in the container will increase, decrease, or stay the same after each of the following disturbances is applied to the original mixture. For each case, assume that all other variables remain constant except for the given disturbance. Select the response which includes the best explanation.

b. The temperature of the equilibrium mixture is increased at constant volume.

c. The volume of the container is decreased at constant temperature.

d. The graphite pellets are pulverized

1 Answer by Expert Tutors

Tutors, sign in to answer this question.
J.R. S. | Ph.D. in Biochemistry--University Professor--Chemistry TutorPh.D. in Biochemistry--University Profes...
4.9 4.9 (32 lesson ratings) (32)
Le Chatelier
C(s) + H2O(g) <==> CO(g) + H2O(g) ∆H = +131 kJ (change sign because reversed the reaction)
(b)  Increase in temperature at constant volume: I think it should ask at constant pressure, because if constant volume, then the pressure will increase with increase in temperature and since the question said to assume that NOTHING else changes, I'll assume that only the temperature is increased in part (b). In that case the moles of CO will increase since heat is a reactant in an endothermic reaction.
(c)  The volume decreases at constant temperature: the moles of CO would decrease because a decrease in volume will cause an increase in pressure and there are more moles of gas on the right than on the left, so reaction shifts to left.
(d)  The graphite pellets are pulverized:  This will increase the RATE of reaction but would not affect the equilibrium concentrations since the pellets are a solid and they do no appear in the equilibrium expression.
You need to learn how to do this and not just ask on the site.