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प्रश्न
Define exothermic and endothermic changes. Give two example in each case.
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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
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संबंधित प्रश्न
State the effect of an endothermic reaction.
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
Identify the endothermic and exothermic reaction.
HCl + NaOH → NaCl + H2O + heat
Give an example of the following chemical changes.
A photochemical reaction involving silver salt.
Name a carbonate which do not decompose on heating.
What do you observe? When
Lead nitrate is heated.
Give an example of the following chemical changes.
An exothermic and an endothermic reaction involving carbon as one of the reactants.
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.
Give an example with a balanced equation, of the following reaction:
photochemical reaction
Complete the statement by filling in the blank with the correct word:
The reaction of hydrogen burning in oxygen to give a neutral liquid is an example of ________ reaction.
