Questions: If the direction of a chemical equation is reversed, the arithmetic sign of its ΔH is changed

Solution Steps

The enthalpy change, $\Delta H$, of a chemical reaction represents the heat absorbed or released during the reaction. If the direction of the reaction is reversed, the process that was previously releasing heat will now absorb it, and vice versa.

When a chemical equation is reversed, the products become reactants and the reactants become products. Consequently, the sign of $\Delta H$ changes. For example, if the forward reaction has $\Delta H = -100$ kJ (exothermic), the reverse reaction will have $\Delta H = +100$ kJ (endothermic).

Final Answer