Question

8
Give reason for the following:
(a) All decomposition reactions are endothermic reactions
(b) Keeping food in airtight containers help in preventing cancer rancidity (c) Silver chloride is stored in dark coloured bottle

Answer 1

1. Decomposition reactions are usually endothermic because they involve breaking of bonds. Breaking bonds requires an input of energy, while forming bonds releases energy. ... But there are decomposition reactions which are exothermic like decomposition of hydrogen peroxide.
2. Keeping food in air tight containers help in preventing rancidity. It does not allow air (oxygen) to come in contact with the food and this prevents oxidation of food. Thus the food never become rancid and its smell and taste remains the same.
3. Silver chloride is a light-sensitive chemical compound andit easily undergoes photolytic decomposition reaction. Silver chloride decomposes into silver and chlorine gas when exposed to sunlight. Hence Silver chloride is stored in dark-colored bottles.