Question

4 moles of A are mixed with 4 moles of B, when
2 mol of C are formed at equilibrium, according to
the reaction, A + B =C + D. The equilibrium
constant is, (=) means reversible reaction

Answer 1

Given

The reaction A + B $\underset{ \longleftarrow }{ \rightarrow}$ C + D

To Find

Equlibrium constant for the reaction.

Solution

Given, 4 moles of A and 4 moles of B are mixed. At equilibrium , 2 moles of C is formed.Let x moles of A and B are dissociated.

$\: \: \: \: \: \: \: \: \: \: \: \: \: A + B \underset{ \longleftarrow }{ \rightarrow} C + D \\ t = o \: \: \: 4 \: \: \: \: \: \: \: 4 \: \: \: \: \: \: \: \: 0 \: \: \: \: \: \: \: 0 \\ t eq 4 - x \: \: \: 4 - x \: \: x\: \: \: \: \: \: \: x$

But, at equilibrium [C] = 2.

Hence, x = 2.

Therefore , concentration of A = [A] = 4 - x = 2 = [B]

[C] = [D] = x = 2.

Hence, equilibrium constant = $\frac{[A] [B]}{[C] [D]}$

= $\frac{2 × 2 }{2 × 2}$

= 1.

$\boxed{ \green{ The\:equlibrium\:constant\:of\:the\:reaction\:is\:1. } }$