Question

1.) Write the equilibrium onstant expression for the reaction below (K_eq):

CH_4(g)+2H₂S_(g) <--> CS_2(g)+4H_2(g)

A reation mixture initially contains 0.50M CH₄ ad 0.75M H₂S. If the equilibrium concenration of H₂ is 0.44M, find the equilibrium constatn (K_c) for the reaction.

2.) Express the equilibrium constant for the following reaction.

P_4(s)+5O_2(g) <--> P₄O_10(s)

Answer 1

1) consider the equation is

CH4 + 2H2S --> CS2 + 4H2

the equilibrium constant is given by

Keq = [CS2] [H2]^4 / [CH4] [H2S]^2

consider the reaction

CH4 + 2H2S --> CS2 + 4H2

using ICE table

[CH4]eq = 0.5 - x

[H2S]eq = 0.75 -2x

[CS2]eq = x

[H2]eq =4x

given

[H2]eq = 0.44

so

4x = 0.44

x = 0.11

so

[CH4]eq = 0.5 - 0.11 = 0.39

[H2S] = 0.75 - 0.22 = 0.53

[CS2] = x = 0.11

[H2] = 0.44

now

Keq = [CS2] [H2]^4 / [CH4] [H2S]^2

Keq = [ 0.11] [0.44]^4 / [ 0.39] [0.53]^2

Keq = 0.0376

so

the equilibrium constant value is 0.0376

2) consider the given reaction

P4 (s) + 502 (g) ---> P401O (s)

we know that

solids are not considered in equilibrium constant expression

so

for this reaction

Kc = 1 / [02]^5