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प्रश्न
Define exothermic and endothermic changes. Give two example in each case.
उत्तर
Exothermic Reaction
The chemical reactions which proceed with the evolution of heat energy are called exothermic reactions.
Examples:
Carbon burns in oxygen to form carbon dioxide and heat energy is produced.
C + O2 → CO2 + Heat
Water added to quick lime (calcium oxide), slaked lime (calcium hydroxide) is produced with a lot of heat energy.
CaO + H2O → Ca(OH)2 + Heat
Endothermic Reaction
The chemical reactions which proceed with the absorption of heat energy are called as endothermic reactions.
Examples:
When nitrogen and oxygen are heated together to a particular temperature of about 3000oC, nitric oxide gas is formed.
N2 + O2 + Heat → 2NO
Calcium carbonate decomposes into carbon dioxide and calcium oxide when heated to a temperature of about 1000oC.
CaCO3 + Heat → CaO + CO2
APPEARS IN
संबंधित प्रश्न
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer.
Heat energy is evolved in these reactions
- Thermal decomposition reactions
- Exothermic reactions
- Endothermic reactions
- None of these
Give scientific reason.
While preparing dilute sulphuric acid from concentrated sulphuric acid in the laboratory, the concentrated sulphuric acid is added slowly to water with constant stirring.
Name a carbonate which do not decompose on heating.
State which type of chemical reaction proceeds with evolution of heat energy.
Complete the statement by filling in the blank with the correct word:
The reaction of coke with steam to give water gas is an example of an __________ reaction.
Chemical reactions may proceed with absorption of heat. Give an example.
Respiration is a ______ change.
Identify the type of chemical reaction given below:
\[\ce{2KClO3 -> 2KCl + 3O2 ^}\]
Complete the following table:
| Chemical Reactions | Name reaction type |
| \[\ce{C(s) + O2(g) -> CO2(g)}\] | (a) ________ |
| \[\ce{Zn(s) + CuSO4(aq) ->}\] (b) _________ | Displacement reaction |
| \[\ce{2Cu(s) + O2(g) ->[heat] 2CuO(s)}\] | (c) _________ |
| \[\ce{C(s) + 2H2(g) -> CH4(g)}\] | (d) _________ |
| \[\ce{CaO(s) + H2O(l) -> Ca(OH)2(aq) + heat}\] | (e) _________ |
| \[\ce{CaCO3(s) + Heat ->}\] (f) _________ | Endothermic Reaction |
Give scientific reason.
While preparing dilute sulphuric acid from concentrated sulphuric acid in the laboratory, the concentrated sulphuric acid is slowly added to water with constant stirring.
