PROBLEM 13Q
What is the enthalpy of reaction (ΔHrxn)? Why is this quantity important?
Solution 13Q
Enthalpy of reaction is defined as the amount of heat absorbed or evolved in
the reaction under constant pressure.
Enthalpy of a reaction is important because, it gives the information about the system and surroundings.
- Most reactions occur under constant pressure conditions.
-
Many reactions do not involve gaseous reactants or products.thus very little work associated with the reaction
E ~
H.
Since, the enthalpy is equal to the heat transfer at constant pressure, so we can determine the nature of a reaction from the sign of H:
-
Exothermic Reaction
H < 0 (negative) and the reaction gives off heat
-
Endothermic Reaction
H > O (positive) and the reaction absorbs heat