Question

What is the enthalpy for reaction 1 reversed?

(A) -94.1 kJ/mol
(B) 94.1 kJ/mol
(C) -188.2 kJ/mol
(D) 188.2 kJ/mol

Answer 1

The enthalpy change (ΔH) for a reversed reaction is the opposite in sign to the forward reaction. Therefore, if the forward reaction has ΔH° = -138.4 kJ, the reversed reaction would have ΔH° = +138.4 kJ/mol, corresponding to option (B) 94.1 kJ/mol.

Step-by-step explanation:

The enthalpy change (ΔH) for reaction 1 reversed is the opposite of what is given for the forward reaction. Since the enthalpy change for the forward reaction is ΔH° = -138.4 kJ, reversing the reaction would change the sign of ΔH. Therefore, the enthalpy for reaction 1 reversed would be +138.4 kJ/mol, which corresponds to option (B) 94.1 kJ/mol in the given choices. It is important to remember that reversing a reaction changes only the sign of ΔH and not its magnitude.