Page 175 - Modern physical chemistry

Problems 167

7.7 For a process between condensed substances obeying the third law, find the limiting slope,
as T approaches zero, of a plot of tlG against T at constant P.
7.8 Calculate a~, Mfl, and tlGo at 298.15 K for the reactions
(a) C2H 4 (g) + H2 (g) ~ C2 H 6 (g),
(b) 2H20(g)+C(S)~C02 (g)+2H2 (g),
from the numbers in tables 7.3 and 7.4.
7.9 From 112 mole nitrogen at 1.000 bar and 25° C and 3/2 mole hydrogen at 5.00 bar. and 25°
C, 1 mole ammonia at 0.1000 bar. and 25° C was obtained. What was tlG?
7.10 Calculate the equilibrium constant at 25° C for

2NO (g) + O2 (g) ( ) 2N0 2 (g)

from numbers in table 7.4.
7.11 Calculate Kp and Kc at 25° C for the reaction
3
-0 2 (g) ( ) 0 3 (g), AG~8.15 = 163.602 kJ.
2
7.12 If at 500 K the fraction of dissociation a of PCls (g) is 0.644 at 1.000 bar, what is this a at
0.100 bar total pressure?
7.13 Determine Kp for the reaction
1
H 2 0 (g) ( ) H2 (g) + -02 (g)
2
at 2500 K and 1.000 bar, where the percentage dissociation of the H 20 is 4.02.
7.14 Calculate the fraction of dissociation and the density of fluorine at 0.400 bar and 1000 K,
where Kp for the reaction
F2 (g) ( ) 2F (g)

is 1.08 x 10- 2 bar.
7.15 The equilibrium

LaCl3 (s) + H20 (g) ( ) LaOCI (s) + 2HCL (g)

was established at 880 K with an HCI pressure of 72.6 torr and an H 20 pressure of 2.94 torr
Determine Kp in bars.
7.16 For the reaction

NH 4HS (s) ( ) NH3 (g) + H2S (g)

parameter Kp equals 5.62 x 10- 2 bar at 20° C. If solid ammonium hydrosulfide is vaporized
at 20° C in a container filled initially with H 2S at 0.395 bar and NH3 at 0.100 bar, what are
the partial pressures when equilibrium is reached?
7.17 For the reaction
F2 (g) ( ) 2F (g)

log Kp is -5.612 at 700 K and -4.098 at 800 K. What is the average Mfl over this temperature
interval?
7.18 Construct an expression for the temperature dependence of the standard enthalpy change
in the reaction
1
C (s) + -02 (g) ~ CO (g), Lllig 98.15 = -110,541 J.
2