Class 10 Corrosion and rancidity

### Topics to be covered

=> Corrosion
=> Rancidity

### 𝐄𝐅𝐅𝐄𝐂𝐓𝐒 𝐎𝐅 𝐎𝐗𝐈𝐃𝐀𝐓𝐈𝐎𝐍 𝐑𝐄𝐀𝐂𝐓𝐈𝐎𝐍𝐒 𝐈𝐍 𝐄𝐕𝐄𝐑𝐘𝐃𝐀𝐘 𝐋𝐈𝐅𝐄

color{green}("𝟏 𝐂𝐨𝐫𝐫𝐨𝐬𝐢𝐨𝐧 :")

As the time passes shiny iron articles get coated with a reddish brown powder when left for some time. This process is commonly known as rusting of iron.

When a metal is attacked by substances around it such as moisture, acids, etc., it is said to corrode and this process is called corrosion. The black coating on silver and the green coating on copper are other examples of corrosion.

color{green}("𝐄𝐅𝐅𝐄𝐂𝐓𝐒 𝐎𝐅 𝐂𝐎𝐑𝐑𝐎𝐒𝐈𝐎𝐍:")

Corrosion causes damage to car bodies, bridges, iron railings, ships and to all objects made of metals, specially those of iron. Corrosion of iron is a serious problem. Every year an enormous amount of money is spent to replace damaged iron.

color{green}("𝟐 𝐑𝐚𝐧𝐜𝐢𝐝𝐢𝐭𝐲")

color{red}(•) When fats and oils are oxidised, they become rancid and their smell and taste change. Usually substances which prevent oxidation (antioxidants) are added to foods containing fats and oil.

color{red}(•) Keeping food in air tight containers helps to slow down oxidation.

color{red}("𝐉𝐔𝐒𝐓 𝐅𝐎𝐑 𝐂𝐔𝐑𝐈𝐎𝐔𝐒")

Chips manufacturers usually flush bags of chips with gas such as nitrogen to prevent the chips from getting oxidised .