Question

A chemical reaction that absorbs heat from the surroundings is said to be __________ and has a __________ ∆H at constant pressure.

A) endothermic, positive
B) endothermic, negative
C) exothermic, negative
D) exothermic, positive

Answer 1

A chemical reaction that absorbs heat from the surroundings is said to be endothermic and has a positive ∆H at constant pressure.

⇒ A) endothermic, positive

What is Enthalpy?

∆H is the change in enthalpy within a system. Enthalpy is the sum of the internal energy within that system.

Equation

H = E + PV = Change in Internal Energy + Pressure * Volume

Step-by-step explanation

In endothermic processes, the amount of energy within the system increases and therefore ∆H increases. In exothermic processes, the amount of energy within the system decreases and therefore ∆H decreases. The best way to remember this is exo is energy exiting the system.