Answer to Question #98739 in General Chemistry for Joe

Question

Q
0.100 mol SO2
and 0.100 mol O2
are introduced into an
evacuated 1.52 L flask at 900 K. When equilibrium is
reached, the amount of SO3
found is 0.0916 mol. Use this
data to determine Kp for the reaction.
2SO2
(g) + O2
(g) 2SO3

Answer 1

$$2SO_2 + O_2 = 2SO_3$$

$[SO_3] = 0.0916mol/1.52L = 0.0603 M$

$[SO_2] = 0.100mol/1.52L - 0.0603M = 0.0055M$

$[O_2] = 0.100mol/1.52L - 0.0603/2M = 0.0356M$

$$K_c = {[SO_3]^2 \over [SO_2]^2[O_2]}$$

$$K_c = {(0.0603)^2 \over (0.0055)^2(0.0356)} = 3.367*10^3$$

$$K_p = K_c(RT)^{2-2-1} = K_c(RT)^{-1} = {K_c \over RT}$$

$$K_p = {3.367*10^3 \over 8.314*900} = 0.4500$$

Answer: 0.4500