The Richard Stockton College of New Jersey
Chemistry Program, School of Natural Sciences and Mathematics
PO Box 195, Pomoma, NJ
CHEM 3410: Physical Chemistry I — Fall 2008
Homework 7
Due in Class: October 20, 2008
1. Consider the equilibrium:
CO(g) + H2O(g)↔C O2(g) + H2(g)
At 1000 K the equilibrium composition of the reaction mixture is:
Substance CO2(g) H2(g) CO(g) H2O(g)
Mole % 27.1 27.1 22.9 22.9
(a) Calculate Kpand ∆G◦
rxn at 1000 K.
(b) Given the answer to park (a), use the tabulated data for ∆H◦
fof the reaction species to
calculate ∆G◦
rxn at 298 K. Assume ∆H◦
rxn is independent of temperature in this range.
2. Consider the gas phase reaction of NO2shown below. At T= 700 K, the equilibrium constant
Kp= 0.379. At a total pressure of 2 atm, the partial pressure of oxygen in the reaction is 0.378
atm at equilibrium. Determine the molar standard state free energy of reaction (∆G◦
rxn) and the
equilibrium composition of the gas mixture (final partial pressure of each component) for these
conditions.
NO2(g)↔NO(g) + 1
2O2(g)
3. Ca(HCO3)2(s) decomposes at elevated temperatures according to the stoichiometric equation:
Ca(H CO3)2(s)−→ CaC O3(s) + H2O(g) + CO2(g)
(a) If pure Ca(HCO3)2(s) is put into a sealed vessel,, the air is pumped out, and the vessel and
its contents are heated, the total pressure is 0.115 bar. Determine KPunder these conditions.
(b) If the vessel initially also contains 0.225 atm H2O(g), what is the partial pressure of CO2(g)
at equilibrium?