Question

For the reaction show:

$3C_2{H}_2\leftrightharpoons C_6{H}_6$

This equilibrium is established when 0.5 mole of benzene is present at a certain temperature. If equilibrium constant of the reaction is 4 litre${}^{-2}$ mole${}^2$. The total number of moles of all the substances present at equilibrium is :

(Note : The reaction is performed in a 1-litre vessel.)

• A. 0.5
• B. 1
• C. 1.5
• D. 2

Answer 1

Answer: (B)

1

Given reaction is : $3C_2{H}_2\leftrightharpoons C_6{H}_6$

$K_c=4.0$

$\left[C_6{H}_6\right]=0.5mol/l$

Formula used $K_c=\left[C_6{H}_6\right]/[C_2{H}_2{]}^3$

Substituting the above values

$0.5=4.0\times [C_2{H}_2{]}^3$

$\left[C_2{H}_2\right]=0.5mol/l$

So, total moles $=0.5+0.5=1mol$