20. Explain the following terms with one example each
.
(a) Corrosion
(b) Rancidity
Answers
a.
The gradual eating up of metals by action of air, moisture or a chemical reaction (such as an acid) on their surface is called corrosion. The most commonly seen example of corrosion of metals is rusting of iron i.e the formation of a brown flaky substance on iron objects on exposure to moist air.
b.
Rancidity is a condition in which the substance with oil and fats get oxidized when they are exposed to air. A substance is said to be rancid when there is a change in smell, taste, and colour. An example of rancidity is when a chips pack is exposed to atmospheric air which results in a change in taste and odor.
Answer:
ANSWER
(a) Corrosion is a natural process, which converts a refined metal to a more stable form, such as its oxide or hydroxide. It is the gradual destruction of metals by chemical reaction with their environment.
Rusting, the formation of iron oxides is a well-known example of electrochemical corrosion.
(b) Rancidity refers to the spoilage of food in such a way that it becomes undesirable and unsafe for consumption. It is the hydrolysis or autoxidation of fats into short-chain aldehydes and ketones which are objectionable in taste and odour.
When rancidity occurs in food, undesirable odours and flavours can result. In some cases, however, the flavours can be desirable (as in aged cheeses).