Discussion Forum



1)

The standard  Gibbs energy change at  300K for the reaction,   $2A\rightleftharpoons B+C$  is 2494.2 J.  At a given time , the composition of the reaction mixture is  $[A]=\frac{1}{2}$ , [B]=2   and   $[C]=\frac{1}{2}$ . The reaction proceeds in the  [ R=8.314 JK/mol, e=2.718]


A) forward direction because Q > $K_{c}$

B) reverse direction because Q >$K_{c}$

C) forward direction because Q < $K_{c}$

D) reverse direction because Q < $K_{c}$

Answer:

Option B

Explanation:

 Given,     $\triangle G^{0}=2494.2J$

  $Q=\frac{[B][C]}{[A]^{2}}=\frac{2\times \frac{1}{2}}{(\frac{1}{2})^{2}}=4$

   $\therefore$

  $\triangle G=\triangle G^{0}+RT lnQ$

              =$2494.2+8.314\times 300 ln 4$

             =28747.27  J

 =  Positive value

  Also, we have

          $\triangle G=RT ln\frac{Q}{K}$

 If  $\triangle G$   is positive , Q>K.

 Therefore,   reaction shifts in reverse direction.