Acid Bases Salts || Class 10 Science || CBSE Notes || Study World || Part 2
Dear Students, Today we are going to share the Notes of Acid Base and Salts. These notes are prepared by the experienced teachers. These notes are free to all the students. These notes has been prepared according to the CCE pattern of school education based on NCERT Syllabus prescribed by the Central Board of School Education for Class X. All the important topics are covered in these notes.
CBSE Class 10 Science Acids Bases and Salts Notes
Some Important Topics
· Salt
¨
Family of Salt
¨
pH of Salt Solution
· Laboratory preparation of Sodium Chloride
· Common Salt
¨
How common salt is obtained:
¨
Common salt from Sea-Water
¨
Common Salt from Underground Deposits
¨
Uses of Common Salt
· Chemicals from Common Salt
· Sodium Hydroxide
¨
Production of Sodium Hydroxide
¨
Uses of Sodium Hydroxide
¨
Uses of Chlorine
¨
Uses of Hydrogen
· Washing Soda
¨
Production of Washing Soda
¨
Property of Washing Soda:
¨
Uses of Sodium Carbonate or Washing Soda
· Baking Soda
¨
Production of Sodium Hydrogen-carbonate:
¨
Uses of Baking Soda
· Bleaching Powder
¨
Preparation of Bleaching Powder:
¨
Property of Bleaching Powder
¨
Uses of Bleaching Powder
· Plaster of Paris
¨
Preparation of Plaster of Paris
¨
Properties of Plaster of Paris:
¨
Uses of Plaster of Paris:
· Water of Crystallization:
¨ Effect of Heat
on Hydrated Salts
Salt
: It is a compound formed by trating a metal with an acid.
e.g.
Zn + H2SO4 ª
ZnSO4 + H2
Na + HCL ª
Nacl + H2
Salts
are also formed when acid reacts with base
e.g.
HCL + NaOH ª NaCl + H2O
H2SO4 + KOH ª
K2SO4 + H2O
The
salts of HCL are called chlorides.
Salt
of H2SO4 are called sulphates and salts of nitric acid
are called Nitrates.
Family of Salt
The
salts having same +ve and ─ve ions are
said to belong to a family of salts.
e.g.
NaCl, Na2SO4, NaNO3 , NaHCO3, CH3COONa
are called sodium salt (Na+ ion common)
pH of Salt Solution:
The acidic solution of many salts are
neutral but some of them produces acidic solution and some produced basic
solution when dissolved in water.
e.g.
Salt Solution
|
pH value
|
Nature
|
NaCl solution
|
7
|
Neutral
|
NH4Cl solution
|
6
|
Acidic
|
Na2CO3 solution
|
9
|
Basic
|
Points to remember:
(i)
The salts of a strong acid and a strong bsse produced neutral solution. e.g.
HCL + NaOH ª
NaCl + H2O
|
(ii)
The salts of strong acid and a weak base produce acidic solution e.g.
HCL + Na4OH ª
NH4Cl + H2O
|
(iii)
The salts of weak acid and a strong base produced basic solution. e.g.
H2CO3 + NaOH ª
Na2CO3 + H2O
|
Laboratory preparation
of Sodium Chloride:- In labourtary Sodium Chloride can be
prepared by treating sodium metal with hydrochloric acid as
Na
+ HCL ª NaCl + H2
|
Sodium
Chloride is also prepared by treating HCL acid with sodium Hydroxide as
NaOH + HCL ª
NaCl + H2O
|
The
salt thus produce is obtained by evaporating all the water.
“Common Salt is
a white powder which is used in preparing food especially vegetable and pulses
etc. Common salt is also known as just Salt”
How common salt is
obtained:
Common
salt is obtained from sea-water and as rock salt.
Common salt from
Sea-Water
Sea
water contains many dissolved salt in it. The major salt present in sea-water
is common salt. Common salt is obtained from sea water by the process of evaporation.
Sea
water is trapped in larger shallow pools and allowed to stand there. The sun’s
heat evaporation the water slowly and common salt is left behind. It is then
purified to obtained pure NaCl.
Common
Salt from Underground Deposits: Rock salt is mined
from the underground deposits just like coal. It is usually brown due to
presence of impurities. The rock salt which we dig out today from the earth was
formed, when the ancient seas dried up by evaporation thousands of year ago.
Uses
of Common Salt:
(1) It is used as a raw
material for making useful chemical. E.g. NaOH
(caustic soda), Na2CO3 (baking soda) NaHCO3 (baking
soda).
(2) In cooking food, it
improves the flavour of food.
(3) It is required by
our body for working of nervous system.
(4) It is used as a
preservative in pickle, meat and fish.
(5) It is used in the
manufacture of soap.
(6) It is used to melt
ice which collects on the road in cold countries.
Chemicals
from Common Salt
Sodium
Hydroxide:- Sodium Hydroxide is commonly known as caustic soda. The chemical formula of
sodium hydroxide is NaOH.
Production
of Sodium Hydroxide
The raw material for
producing Sodium Hydroxide is NaCl. Sodium Hydroxide is produced by the
electrolysis of concentrated aqueous solution of sodium chloride called brine.
When electricity is
passed through a concentrated solution of NaCl called brine, it decomposes to
form sodium hydroxide, chlorine and hydrogen.
During electrolysis
chlorine gas is produced at the anode
and hydrogen gas is produced at the cathode.
Sodium hydroxide solution is formed near the cathode.
The process of
electrolysis of sodium chloride solution is
chlor for chlorine and alkali for sodium hydroxide.
Three useful product
obtained from brine are sodium hydroxide
chlorine and hydrogen. This
products have lot of uses which are as follow:
Uses
of Sodium Hydroxide
(1) It is used for
making detergent.
(2) It is used for
making artificial textile fibre (rayon).
(3) It is used in the
manufacture of paper.
(4) It is used in
purifying bauxite ore from which aluminum metal is extracted.
Uses
of Chlorine
(1) It is used to sterilize drinking
water.
(2) It is used in the production of
bleaching powder.
(3) It is used in the production of HCL.
(4) It is used to make plastics such as
(PVC) Polyvinyl chloride.
(5) It is used for making solvent for
dry cleaning.
Uses
of Hydrogen
(1) It is used in the production of HCL.
(2) It is used to make ammonia for
fertilizer.
(3) It is also used to make methanol (CH3OH)
(4) Liquid hydrogen is used as a fuel
for rocket.
Washing Soda
Washing soda is sodium carbonate containing 10 molecule
of water of crystallization. The formula
for washing soda is Na2CO310H2O.
Sodium carbonate
without water of crystallization is an anhydrous sodium carbonate known as soda
ash.
Production
of Washing Soda
Washing soda is produced from NaCl in
the following three steps:
(1) Firstly brine is react with ammonia
and CO2 to obtain sodium
hydrogen carbonate.
(2) In the second step, sodium hydrogen
carbonate is decomposes to form sodium carbonate.
(3) In the third step, the anhydrous
sodium carbonate is dissolved in water and re-crystallized to form washing soda.
Property of Washing Soda:
(a) Washing soda is transparent
crystalline solid.
(b) It is soluble in water.
(c) Solution of washing soda is alkaline
in nature.
(d) It has cleansing property in water.
Uses of Sodium
Carbonate or Washing Soda
(i) Washing soda is used as a cleansing
agent for domestic purpose like washing clothes.
(ii) It is used in removing permanent
hardness of water.
(iii) It is used in the manufacture of glass,
soap and paper.
(iv) It is used in the manufacture of sodium
compound such as borax.
Baking
Soda
The chemical name of
baking soda is sodium hydrogen carbonate.
The formula of baking soda is NaHCO3. It is also called sodium bicarbonate.
Production of Sodium Hydrogen-carbonate:
Sodium hydrogen-carbonates is produced by reacting brine with ammonia and carbon dioxide.
Properties of Sodium Hydrogen-carbonate:
(a) It consists of white crystal and are
soluble in water.
(b) It is non-corrosive base. The
solution of sodium hydrogen carbonate is mildly alkaline.
(c) On decomposes, it give sodium carbonate
with the evolution of CO2 gas.
Uses
of Baking Soda
(a) It is used as an antacid in the
medicine to remove acidity of the stomatch.
(b) It is used in the making baking
powder (used in the making cake and bread etc.)
(c) Baking soda is also used in the fire
extinguishers.
Bleaching
Powder
Bleaching
powder is calcium oxy-chloride. The
chemical formula of bleaching powder is a CaOCl2. It is also called
chloride of lime.
Preparation of Bleaching
Powder:
Bleaching
powder is prepared by passing chlorine gas over dry slaked lime.
Property of Bleaching Powder
(1) It is a white powder which gives a
strong smell of chlorine.
(2) It is soluble in cold water.
(3) It reacts with dilute acids to
produce chlorine.
Uses of Bleaching Powder
(a) It is used for bleaching cotton and
linen in textile industry.
(b) It is also used for bleaching clothes
in laundry.
(c) Bleaching powder is used for
disinfecting drinking water.
(d) It is also used in the manufacture
of chloroform ( CHCl3).
(e) It is also used for making wool un-shrinkable.
(f) It is also used in as an oxidizing
agent in chemical industries.
Plaster of Paris
Plaster
of Paris is Calcium sulphate hemihydrate or Calcium sulphate half-hydrate. The
formula for POP is CaSO4 ½H2O. The name of plaster of paris
come from the fact that it was the first of all made by heating gypsum which is
mainly found in Paris.
Preparation
of Plaster of Paris
Plaster of Paris is
prepared by heating gypsum to a temperature of 1000C in a Kiln. When
gypsum is heated to a temperature of 1000C, it loose three fourth of
water of crystallization and forms plaster of paris:
The formula of plaster
of paris can we also be written as 2CaSO4 H2O. It means
CaSO4 share one molecules of water.
Properties
of Plaster of Paris:
(1) It is a white powder.
(2) Plaster of paris has a very
remarkable property of setting into a hard mass on wetting with water.
(3) Plaster of paris should be stored in
moisture proof container.
Uses
of Plaster of Paris:
(1) It is used in hospital for setting
fracture bone in the right position.
(2) It also used for making toys,
decorative materials cheap ornaments and blackboard chalk etc.
(3) It can be used as a fire proofing
material.
(4) It is also used in laboratory for
sealing air gap in the apparatus.
(5) It is used in making the surface
smooth before painting them; like the ball of the house.
Water of Crystallization:
The water molecule
which form part of the structure of a crystal of a salt are called water of
crystallization.
The salt which contain
water of crystallization are called hydrated salt.
Or
The water molecules
which chemically combined with the molecules of salt during the preparation of
this crystals and become a part of it is
called water of crystallization, and salt are called hydrated salts.
e.g. CuSO4
5H2O, Al2O3 2H2O, Na2CO3
10H2O,
Effect
of Heat on Hydrated Salts:
Hydrated salts loose
their water of crystallization when heated strongly and their salts become unhydrous.
E.g. CuSO4 5H2O, (copper sulphate penta hydrade or
hydrated copper sulphate) (Blue and colourless)
CuSO4 5H2O,
ª
CuSO4 + 5H2O
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