10 Examples of Endothermic Reactions with Equations

Here you will find 10 examples of endothermic reactions with equations with detailed explanations.

 10 Examples of Endothermic Reactions with Equations

What are endothermic reactions?

The chemical reactions in which energy is absorbed from surroundings are called endothermic reactions.

The energy in the form of heat, light, or electricity is supplied to complete the reactions.

 

Examples of Endothermic Reactions

Following are the 10 examples of endothermic reactions.

   1. Reaction between nitrogen and oxygen

   2. Thermal decomposition of calcium carbonate

   3. Dissolving ammonium nitrate in water

   4. Photosynthesis

   5. Melting of ice

   6. Electrolysis of water

   7. Decomposition of silver bromide

   8. Decomposition of lead nitrate

   9. Dissolving potassium chloride in water

  10. Evaporation of water

   1.  Reaction between nitrogen and oxygen

   When nitrogen gas reacts with oxygen gas, energy from surroundings (180.5kJ) is absorbed.

     N₂ + O₂ +(180.5kJ)→2NO

2.   Thermal decomposition of calcium carbonate

When calcium is heated, it breaks down into calcium oxide and carbon dioxide. This is an endothermic reaction

  `CaCO_{3(s)} \overset{heat}{\rightarrow}CaO_{(s)} + CO_{2(g)}`

3. Dissolving ammonium nitrate in water

  When ammonium nitrate is dissolved in water, it feels cold which indicates that it is an endothermic reaction.

        NH₄NO₃ +H₂O →NH_4(aq) + NO_3(aq)

4.   Photosynthesis

 Photosynthesis is the process through which green plants prepare food in the presence of sunlight (light energy), so this is an endothermic reaction.

   6CO₂ + 6H₂O →C₆H₁₂O₆ + 6O₂

5.   Melting of ice

 Ice is a solid form of water (H₂O), when ice absorbs energy from its surroundings, it starts melting. So this is also an endothermic reaction.

       `H_2O_{(s)} \overset{heat}{\rightarrow} H_2O_{(l)}`

Actually, this is a physical change as no new substance is formed.

6.   Electrolysis of water

When electric current (energy in the form of current)is passed in water, it breaks down into Hydrogen and oxygen. This process is known as electrolysis.

 

 

  `2H_2O_{(s)} \overset { current} {\rightarrow} 2H_{2(g)}  + O_{2(g)}`

7.    Decomposition of silver bromide

 In the presence of sunlight, silver bromide breaks down into silver and bromine.

 `2AgBr  \overset{sunlight}{\rightarrow}  → 2Ag  + Br_2`

8.    Decomposition of lead nitrate

  Lead nitrate breaks down when heated (energy in the form of heat), so it is an endothermic reaction.

     `2Pb(NO_3)_2 \overset{heat}{\rightarrow} 2PbO + 4NO_2 + O_2`

9.     Dissolving of potassium chloride

  When potassium chloride is added to water, it absorbs heat from the surroundings, so it is an endothermic reaction.

   KCl + H₂O → K_(aq)  + Cl_(aq)

Potassium chloride is an ionic compound so it ionized in water  in the form of `K^+` and `Cl^-` ions

10.  Evaporation of water

 Water absorbs heat from surroundings and changes into vapors, this is called evaporation. This is an endothermic reaction.

  

  `H_2O_(l)   \overset{heat}{\rightarrow} H_2O_(g)`

Actually evaporation of water is a physical change, not a chemical change as no new product is formed during the process.

Only the physical state of the water changes. 

So, these are the common  10 examples of endothermic reactions.

✅✅Related Topics 

1. Important Chemical Reactions

                                      👇 Quiz 👇

FAQs

 

1. Evaporation of water is an example of which reaction?

Ans – Electrolysis of water is a decomposition reaction.

2. Is   evaporation of water an exothermic process

Ans -  No, evaporation of water is not an exothermic reaction. It happens when water absorbs heat from surroundings so it is an endothermic reaction.

3. Is the evaporation of water a chemical change?

Ans  - Evaporation of water is not a chemical change as it only involves a change in the physical state of water from liquid to vapours.

4. Write the chemical name and formula of the brown gas produced during the thermal decomposition of lead nitrate.

Ans - Nitrogen dioxide (NO₂)

5. Which gas is emitted on anode in the electrolysis of water?

Ans – Oxygen gas is emitted on the anode during the electrolysis of water.

6. What are the products of electrolysis of water

Ans.  – Oxygen and hydrogen gases