Question

What does one mean by exothermic and endothermic reactions? Give examples.​

Answer 1

Exothermic reaction :

When energy is released in the form of heat during the reaction, it is called an exothermic reaction. The heat evolved is shown by a plus sign on the right-hand side of the equation.

For example :

$\sf N_{2} (g) + 3 H_{2} (g) \longrightarrow 2NH_{3} (g) + 92 kJ$

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Endothermic reaction :

When energy is absorbed as heat during a reaction it is called an endothermic reaction the heat absorbed is shown by a plus sign on the left hand side of the equation or with the negative side on right hand side.

For example :

$\sf N_{2} (g) + O_{2} (g) + 180 kJ \longrightarrow 2NO (g)$

⠀ ⠀⠀ ⠀ ⠀⠀ OR

$\sf N_{2} (g) + O_{2} (g) \longrightarrow 2NO (g) - 180 kJ$

Answer 2

Answer:

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reaction in which heat energy is liberated by the reactants is called exothermic reaction. eg: Carbon + Oxygen gives Carbon Dioxide + Q. reaction in which heat energy is absorbed by the reactants is called endothermic reaction. eg: Nitrogen + Oxygen gives 2 nitrous oxide (2NO) - Q.