When heated, hydrogen sulfide gas decomposes according to the equation: 2H2S(g)  2 H2(g) + S2(g) A 3.75 gram sample of H2S(g) is introduced into an evacuated rigid 0.75 L container. The sealed container is heated to 483 K and 2.42 x 10 –2 mol of S2 gas is present at equilibrium. a. Write the expression for the equilibrium constant, Kc, for the reaction above.

Explanation:

Moles of   =

Volume of solution = 0.75  L

Initial concentration of =

Equilibrium concentration of =

The given balanced equilibrium reaction is,

Initial conc.              0.15 M        0        0

At eqm. conc.     (0.15-2x) M   (2x) M   (x) M

The expression for equilibrium constant for this reaction will be,

Now put all the given values in this expression, we get :

Given : x = 0.032 M

the correct answer would be d. hope this !