Question

A reaction having equal energies of activation for forward and reverse reactions has:
A.\[~\mathbf{\Delta }S=0\]
B.\[~\mathbf{\Delta }G=0\]
C.\[~\mathbf{\Delta }H=0\]
D.\[~\mathbf{\Delta }H=~\mathbf{\Delta }g=~\mathbf{\Delta }S=0\]

Answer 1

Hint: The change in enthalpy for a reaction is actually the difference in energies in forward and backward reaction. When these energies are equal, the difference is zero.

Complete step by step solution:
The term \[\mathbf{\Delta H}\] represents enthalpy of a system, in chemistry. Enthalpy is the additional product of the internal energy of a system, along with the system’s volume and the pressure too. It is a state function and is used in a lot of measurements.
It shows the capacity of a system to do non-mechanical work, or radiate heat energy. In chemistry, change of enthalpy is calculated instead of the absolute enthalpy, because it is not feasible for us to know the initial point, rather the origin.
There is a condition while measuring the difference in enthalpy and that is, pressure should remain constant during the whole process.
It is to be noted that a chemical reaction that has equal energies of activation for both the forward as well as the reverse reaction has no difference of enthalpy. As the enthalpies are the same, there is no difference between them, so we can say that \[\mathbf{\Delta H}=0\] for the reaction.

Which gives our answer as option C.

Note: Enthalpy itself is a very big topic. There are various types of enthalpies like enthalpy of atomisation, enthalpy of fusion, enthalpy of formation, enthalpy of adsorption, enthalpy of hydration, etc. In all these, the differences in enthalpies are taken from final state to the initial state. Enthalpy can never become a path function as it does not depend on the pathway of the reaction.