Chapter EN, Problem 5PQ

Interpretation Introduction

Interpretation:

The diagram that best represents change in enthalpy for dissolution of ${\text{Na}}_{\text{2}}{\text{S}}_{\text{2}}{\text{O}}_3\cdot 3{\text{H}}_{\text{2}}\text{O}$ in water has to be identified.

Concept Introduction:

Change in enthalpy $\left(\Delta H\right)$ can have two values: If the reaction is endothermic, more energy needs to be supplied to the system than that released by it. So $\Delta H$ comes out to be positive. If the reaction is exothermic, more energy is released by the system than that supplied to it. So $\Delta H$ comes out to be negative.