CHEMICAL
REACTIONS AND EQUATIONS-
The effects of oxidation reactions in everyday life
CORROSION
The phenomenon due to which the surface of metal is
attacked by air, water and chemicals present in the atmosphere (acids), is
called corrosion.
Some common examples of corrosion:
i. Rusting of iron
– iron when reacts with moist air forms a layer of rust over its surface
Fe + 3 O2 + 2 xH2O → 2 Fe2O3. xH2O
Hydrated iron (III) oxide
(rust)
ii. Tarnishing of silver
– silver is a least reactive metal, yet it reacts with hydrogen sulphide to
form black layer of silver sulphide.
2Ag
+ H2S → Ag2S + H2
Silver Hydrogen Silver
Sulphide Sulphide
iii. Green coating on
the surface of copper – copper when exposed to air and moisture forms a green
layer of basic copper carbonate.
2Cu + O2 + CO2 + H2O → CuCO3 + Cu (OH)2
(Basic copper carbonate)
Green coating
1.
Necessary
conditions for corrosion –
i.
Presence of air
ii.
Presence of
water
2.
Effects of
corrosion – corrosion causes damage to car bodies, bridges, iron railings,
ships and to all objects made of metals.
3.
Methods of
prevention –
i.
By painting
ii.
By greasing
iii.
By oiling
iv.
Galvanisation
v.
Using alloys
Rancidity
It is
the process of oxidation fat and oil present in the food materials, which
result into bad taste and foul smell.
1.
Methods to
prevent rancidity
i.
Using air tight
containers
ii.
Refrigeration
iii.
Flushing of
nitrogen gas in chips packet
iv.
By adding
antioxidants e.g. BHA and BHT
Prepared by Ms. Priti Maan Uploaded by Amit Manhas
Prepared by Ms. Priti Maan Uploaded by Amit Manhas
0 Comments