Question

The value of Kc for the thermal decomposition of hydrogen sulfide, shown below, is 2.2 x 104 at 1400 K. 2H,S(g) 2H2(g) +S2(g) 3rd attempt Feedback Inul See Periodic Table See Hint A sample of gas in which (H2S] -4.25 M is heated to 1400 K in a sealed vessel. After chemical equilibrium has been achieved, what is the value of [H,S]? Assume no H2 or Sy was present in the original sample. M

Answer 1

Answer -

Given,

Kc = 2.2 * 10-4

Temperature = 1400 K

Initial [H2S] = 4.25 M

Equilibrium [H2S] = ?

2 H2S (s) $\rightleftharpoons$ 2 H2 (g) + S2 (g)

First, we have to make ICE Table,

	H2S	H2	S2
I	4.25	0	0
C	-2X	+2X	X
E	4.25-2X	2X	X

Kc = [H2]2[S2] / [H2S]2

2.2 * 10-4 = (2X)2(X) / (4.25-2X)2

2X is very smaller than 4.25 So, 4.25-2X $\approx$ 4.25

0.00022 = 4X3 / (4.25)2

0.00022 = 4X3 / 18.0625

0.00022 * 18.0625 = 4X3

0.00397375 = 4X3

X3 = 0.0009934375

X = 0.0998 M

So, Equilibrium [H2S] = 4.25-2(0.0998) = 4.05 M [ANSWER]