問化學關於organic chemistry~~

Exothermic reaction is a chemical reaction in which the system releases heat to the surrounding.
Combustion reactions are exothermic reactions.
(1) Burning of methanol
CH3OH(l) + 1.5 O2(g) = CO2(g) + 2H2O(g) +726 kJ H = - 726 kJ

(2) Combustion of hydrogen
H2(g) + 0.5O2 = H2O(l) + 285.8 kJ H = - 285.5 kJ

Endothermic reaction is a chemical reaction in which the system absorbs heat from the surrounding.
(1) Electrolysis of water
H2O(l) + 285.5 kJ = H2(g) + 0.5O2 H = + 285.5 kJ

(2) Cold pack
NH4NO3(s) + H2O(l) + energy = NH4NO3 (aq)
~ This is not a proper chemical equation.

The cold pack is an example of an endothermic reaction. The pack contains ammonium nitrate and water separated by a barrier. When the barrier is broken and ammonium nitrate is mixed with water, energy is absorbed from the water, and the temperature of the pack goes down. When the cold pack is placed on the injured area, heat transfers from the athlete to the cold pack. (as the reaction proceeds.) This causes the injury to cool, thus reducing swelling, pain and tissue damage.

Note: H denotes enthalpy change

不知道你的 worksheet. 是什麼 organic chemistry? Organic Chemistry 是一非常大的 subject.
例如 Exothermic/Endothermic reaction 是 Physical Chemistry 其中 Thermochemistry 一部分. Please be more specific.