Question

Write the chemical equation of the reaction in which the following changes have taken place with an example of each:
(i) Change in colour
(ii) Change in temperature
(iii) Formation of precipitate

Answer 1

heya!!

here is ur answer ........
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◆change in colour .
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potassium dichromate solution and sulphur dioxide are characterised by change in colour from Orange to green.

◆Change in temperature
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chemical reaction between quicklime and water is characterised by change in temperature

●CaCO3(s)+Heat-----------)Hai(s)+CO2(g)

◆formation of precipitate
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Ca(OH)2(aq)+CO2---------;-)CaCO3(s)【precipitate】+H2O(I)


hope it help you ☺

@rajukumar☺

Answer 2

(i) Change in color: Some "chemical reactions" are featured by "change in color". "Citric acid" reacts with "potassium permanganate", then the purple colour disappears.  

(ii) Change in temperature: Chemical reactions are done but absorbing or releasing heat energy. If "heat energy" is "absorbed" by the chemical reaction is called endothermic reactions. If "heat energy" is "released" by the chemical reaction is called exothermic reactions. "Quick lime" reacts with water then slaked lime is formed and a lot of heat energy is produced.  

(iii) Formation of precipitate: Some "chemical reactions" are featured by "precipitate". Potassium iodide reacts with lead nitrate to form a yellow precipitate of "lead iodide".