01 Redox Equilibrium
02 Carbon Compounds
03 Thermochemistry
04 Polymers
05 Consumer and Industrial Chemistry

3.1.2 Exothermic Reactions

Exothermic Reaction

  1. Exothermic reaction is the chemical reaction that releases heat to the surrounding.
  2. When energy is given off during a chemical reaction, the temperature of the surrounding will increase.

Example of Exothermic Reaction

Reaction Equation
Neutralization

Diluted sulphuric acid is neutralized by sodium hydroxide aqueous

H2SO4 + 2NaOH → Na2SO4 + 2H2O
Acid + carbonate

Reaction between hydrochloric acid and sodium carbonate

2HCl + Na2CO3 → 2NaCl + CO2 + H2O
Calcium oxide + water
CaO + H2O → Ca(OH)2
 
Water + dehydrated copper(II) sulphate
CuSO4 + xH2O → CuSO4xH2O
Dissolve NaOH and KOH in water
NaOH + water → Na+ + OH
KOH + water → K+ + OH
Reaction between alkali metal (Li/Na/K) and water

Sodium + Water

2Na + 2H2O → 2NaOH + H2
 
Reaction between reactive metal (Mg/Al/Zn/Fe) and diluted acid

Magnesium + Nitric acid

Mg + 2HNO3 → Mg(NO3)2 + H2
Combustion

Combustion of methane

CH4 + 2O2 → CO2 + 2H2O

Others

  • Rusting
  • Dilution of concentrated sulphuric acid/ concentrated nitric acid or others acid in water.
  • Crystallization of sodium tiosulphate.
  • Change of state from gaseous state to liquid state and liquid state to solid state.