Question

Read the following statement carefully and then answer the questions that follow.

The equilibrium constant (Kp) for the reaction of solid carbon with carbon dioxide producing carbon monoxide at 850 ºC, has a value of 0.70:

A. Write the reaction that takes place and the corresponding half-reactions.

B. Calculate the partial pressure of the equilibrium if you initially have 1 mole of CO2, in a 30 L container and at a temperature of 850 ºC, in addition to solid carbon.

C. Calculate the partial pressures of the equilibrium if you initially have 1 mole of CO2, under the same conditions as the previous section, but in a container whose volume is half. D. If the reaction is known to be endothermic, where will the system move if the temperature increases to 1000 ºC?

E. Assuming that the carbon monoxide formed in the above reaction is separated and a solution prepared by adding 1 L of water to said oxide; What is the final concentration in units of normality that would be obtained?

Answer 1

A.

The overall reaction is

The corresponding half reactions are

B.

Initial partial pressure of carbon dioxide

Initial partial pressure (atm)	3.07	0
Change in partial pressure (atm)	-x	+2x
Equilibrium partial pressure (atm)		2x

The equilibrium constant

This is quadratic equation with solution

or

Negative value is discarded as partial pressure cannot be negative.

C.

Volume is reduced to half from 30 L to 15 L.

Initial partial pressure of carbon dioxide

Initial partial pressure (atm)	6.14	0
Change in partial pressure (atm)	-x	+2x
Equilibrium partial pressure (atm)		2x

The equilibrium constant

This is quadratic equation with solution

or

Negative value is discarded as partial pressure cannot be negative.

D.

Reaction is endothermic. Heat is absorbed during the forward reaction

When temperature is raised from 850 deg C to 1000 deg C, heat is added to the system and the equilibrium will shift in the forward direction. More and more carbon will combine with carbon dioxide to form more and more carbon mono-oxide.