Question

what is exothermic and endothermic reaction​

Answer 1

Exothermic reactions may occur spontaneously and result in higher randomness or entropy (ΔS > 0) of the system. They are denoted by a negative heat flow (heat is lost to the surroundings) and decrease in enthalpy (ΔH < 0). In the lab, exothermic reactions produce heat or may even be explosive.

There are other chemical reactions that must absorb energy in order to proceed. These are endothermic reactions. Endothermic reactions cannot occur spontaneously. Work must be done in order to get these reactions to occur. When endothermic reactions absorb energy, a temperature drop is measured during the reaction. Endothermic reactions are characterized by positive heat flow (into the reaction) and an increase in enthalpy (+ΔH).

Answer 2

Answer:

Exothermic Reaction:

An exothermic process releases heat, causing the temperature of the immediate surroundings to rise.

Example:

#Combustion of fuels such as wood, coal and oil petroleum.

#Thermite reaction.

#Reaction of alkali metals and other highly electropositive metals with water.

Endothermic Reaction:

An endothermic process absorbs heat and cools the surroundings.”

Example:

#Melting ice cubes.

#Melting solid salts.

#Evaporating liquid water.