Question

Give reasons for the following
1. All decomposition reactions are endothermic reactions
2. Colour of copper Sulphate solution changes when an iron nail is dipped in it
3. Respiration is an exothermic reaction

Answer 1

Hey here’s your answer

1. All decomposition reactions involve the absorption of energy ( mostly heat energy). Endothermic reactions are the reactions which proceed with the absorption of heat energy. As absorption of heat occurs, therefore, all decomposition reactions are endothermic reactions.

2. When an iron nail is dipped in blue coloured copper sulphate solution, the colour of the copper sulphate solution changes because iron ( more reactive) displaces copper (less reactive).

3. In respiration, the oxygen we inhale burns the food in our body thereby releasing heat energy. Exothermic reactions are the chemical reactions that proceed with the release of heat energy. As there is release of heat energy, therefore, respiration is an exothermic reaction.


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Answer 2

Answer:

1) As absorption of heat occurs, therefore, all decomposition reactions are endothermic reactions.

2) When an iron nail is dipped in blue coloured copper sulphate solution, the colour of the copper sulphate solution changes because iron ( more reactive) displaces copper (less reactive).

3) Respiration is considered as an exothermic reaction because in respiration oxidation of glucose takes place which produces large amount of heat energy.