Question

Which describes an endothermic reaction?
A. Positive $\Delta H$
B. Negative $\Delta H$
C. Positive $\Delta G$
D. Negative $\Delta G$

Answer 1

Endothermic reactions are those chemical reactions in which the reactants absorb heat energy from the surroundings and form products. These reactions lower the temperature of their surrounding area and create a cooling effect in the surrounding area.

Complete answer:
Chemical processes as well as physical processes can also be endothermic in nature for example when ice cubes absorb heat energy from the surroundings they melted in the form liquid water during this process no chemical bonds are broken or formed only change of state of matter occurs. In case of chemical processes when a chemical bond is broken, it is usually accompanied by a release of energy. Similarly for formation of chemical bonds it requires any source of energy. The energy supplied or released can be in various forms like heat, light and electricity. Endothermic reactions generally involve the formation of chemical bonds through the absorption of heat from the surroundings. The term Endo is generally taken from the greek word whose meaning is within.
As we discussed in endothermic reactions the system absorbs heat from the surroundings therefore entropy of the surrounding decreases and enthalpy change i.e. $\Delta H$is positive.

Hence option A is the correct answer.

Note:
The process of sweating is also an example of an endothermic process as sweat produced on the surface of the skin absorbs heat from the skin to evaporate and create a cooling effect. Hence we can say that the human body exploits the endothermic nature of evaporation to cool itself.