The energies of activation for forward and reverse reactions for A_{2}+B_{2}\rightleftharpoons 2AB\; are\; 180\; kJ\; mol^{-1}\; and\; 200\; kJ\; mol^{-1} respectively. The presence of a catalyst lowers the activation energy of both (forward and reverse) reactions by 100\; kJ\; mol^{-1} . The enthalpy change of the reaction (A_{2}+B_{2}\rightarrow 2AB)

in the presence of a catalyst will be  (in\; kJ\; mol^{-1})

  • Option 1)

    20

  • Option 2)

    300

  • Option 3)

    120

  • Option 4)

    280

 

Answers (1)
D Divya Saini

As we learnt in 

Catalyst -

A catalyst is a surface that increases the rate of a chemical reaction without itself being used up. It remains unchanged chemically providing an alternate path for the reaction at an accelerated rate by lowering the activation energy. 

- wherein

 

 Enthalpy change of reaction do not change by adding catalyst.

 

\bigtriangleup H = 200-180 = 20 KJmol^{-1}


Option 1)

20

This option is correct

Option 2)

300

This option is correct

Option 3)

120

This option is incorrect

Option 4)

280

This option is incorrect

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