Endothermic Reactions

Endothermic Reaction

  1. Endothermic reaction is a chemical reaction that absorbs heat from surroundings.
  2. When energy is taken from the surrounding during a chemical reaction, the temperature of the surrounding will decrease.

Example of Endothermic Reaction

Decomposition of carbonate metal by heat

Decomposition of calcium carbonate by heat

CaCO3 → CaO + CO2
Decomposition of nitrate metal by heat

Decomposition of Lead Nitrate by Heat

2Pb(NO3)2 → 2PbO + 4NO2 + O2
Dissolve potassium nitrate, ammonium nitrate or ammonium chloride in water.

KNO3 + Water → K+ + NO3
NH4NO3 + Water → NH4+ + NO3
NH4Cl + Water → NH4+ + Cl-
Reaction of heat on hydrated copper(II) sulphate.

CuSO4xH2O → CuSO4 + xH2O


  • Change of physical state from solid to liquid or from liquid to gas.

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