Question

For the reaction 3A(g) + B(g) 20(g) at a given temperature, Kc = 9.0. What must be the concentration
of (C) at equlibrium, if a mixture of 2.0 mol each of A, B and C exist in equilibrium ?
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Answer 1

The equilibrium reaction is 3A(g)+B(g)⇌2C(g).

Let V be the volume of the flask.

The equilibrium number of moles of A,B and C are 2,2 and 2 respectively.

The equilibrium concentrations of A,B and C are V2,V2 and  V2 respectively.

The expression for the equilibrium constant is Kc=[A]3[B][C]2.

Substituting values in the above expression, we get

9.0=(V2)3(V2)(V2)2.

Thus, V=6L.