chemical reactions and equations — Science STD 10 — Question
Gujarat BoardEnglish MediumSTD 10Sciencechemical reactions and equations3 Marks
Question
Explain the following terms with one example each:
$(a)$ Corrosion
$(b)$ Rancidity
✓
Answer
$(a)$ Corrosion :
Metal gets corroded in the presence of acid and moisture.
This process is called corrosion.
Rusting of iron, tarnishing of silver, green coating of salt on the utensils of copper are the examples of corrosion.
Due to corrosion, iron gets covered with a red brown substance (powder) which is called rusting of iron (or corrosion).
Corrosion causes damage to the articles (objects) made from iron such as car-bodies, bridges, iron railings, ships, etc. There is a huge expenditure to control corrosion.
Rusting can be prevented by painting the surface of iron or coating the surface of iron with more reactive metal $(Zn)$.
Prevention of corrosion by coating iron surface with zinc is called galvanization.
$(b)$ Rancidity :
When food containing oil and fat is kept in an open air, it undergo oxidation and become rancid; due to which their smell and taste changes.
This process is called rancidity.
Usually, to avoid rancidity in food containing oil and fat, substances are added which prevent oxidation.
Such substances are known as antioxidant substances.
Food kept in air-tight containers helps to slow down its oxidation and rancidity is retarded.
Manufacturers of potato chips flush bags of chips with gas such as inactive nitrogen gas as antioxidant to prevent the oxidation of potato chips.
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