Acid Bases Salts | Class 10th Science | CBSE Notes | Study World | Part 2

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

Click Here : Acid Bases Salts Part 1

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

Click Here : Acid Bases Salts Part 1