question_answer

For an endothermic reaction, energy of activation is \[{{E}_{a}}\] and enthalpy of reaction is \[\Delta H\] (both of these in kJ/mol). Minimum value of \[{{E}_{a}}\]  will be                                                               [AIPMT (S) 2010]

A)  less than \[\Delta H\]   

B)       equal to \[\Delta H\]

C)  more than \[\Delta H\] 

D)       equal to zero

Correct Answer: C

Solution :

Key Idea In endothermic reactions, energy of reactants is less than that of the products. Potential energy diagram for endothermic    reactions is

where, activation energy of forward reaction  activation energy of backward reaction  enthalpy of the reaction From the above diagram,

Thus,