In: Chemistry
Use ?G?f values from Appendix IIB to calculate the equilibrium constants at 25 ?C for each of the following reactions.
a. 2NO2(g)?N2O4(g)
b. 3/2H2(g)+1/4P4(g)?PH3(g)
a. 2NO2(g)---------------------> N2O4(g)
Grxn = Gproducts - Greactants
= 99.8 - (2 x 51.3)
= -2.8 kJ / mol
Grxn = - R T ln K
-2.8 = -(8.314 x 10^-3 ) x 298 x ln K
ln K = 1.13
K = 3.10
equilibrium constant = K = 3.10
b. 3/2H2(g)+1/4P4(g)-----------------> PH3(g)
Grxn = Gproducts - Greactants
= 13.5 - (1/4 x 24.4)
= 7.4 kJ / mol
Grxn = - R T ln K
7.4 = -(8.314 x 10^-3 ) x 298 x ln K
ln K = -2.99
K = 0.050
equilibrium constant = K = 0.050