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Salts

• By Rohit Pratti

Table Of contentsTable Of contentsCategories of saltsCategories of salts(a) Salts of a strong acid and a strong base(a) Salts of a strong acid and a strong base(b) Salts of a strong acid and weak base(b) Salts of a strong acid and weak base(c) Salts of a strong base and weak acid(c) Salts of a strong base and weak acidCommon Salt Common Salt Preparing NaOH from NaCl Preparing NaOH from NaCl Preparing Bleaching powder from NaClPreparing Bleaching powder from NaClPreparing Baking Soda from NaClPreparing Baking Soda from NaClPreparing washing soda from NaClPreparing washing soda from NaClWater of crystallizationWater of crystallizationPlaster of ParisPlaster of ParisSaltsSalts

SaltsSalts

Salts are the ionic compounds formed by Salts are the ionic compounds formed by the combination of positive charge (A.K.A the combination of positive charge (A.K.A cation) and the negative charge (A.K.A cation) and the negative charge (A.K.A anion).anion).

Salts are electrically neutral.Salts are electrically neutral. Generally, the positive is a metal ion Generally, the positive is a metal ion

excepting ammonium ion (NHexcepting ammonium ion (NH44++) which is a ) which is a

non metallic ion.non metallic ion.

Categories of SaltCategories of Salt

There are three categories of salt There are three categories of salt they are:-they are:-

1.1. Salts of a strong acid and a strong Salts of a strong acid and a strong basebase

2.2. Salts of strong base weak acidSalts of strong base weak acid

3.3. Salts of strong acid and weak base.Salts of strong acid and weak base.

Salts of a Strong Acid and strong Salts of a Strong Acid and strong basebase

They are neutral with a pH value of 7.They are neutral with a pH value of 7. These salts produce a strong base and These salts produce a strong base and

strong acid when dissolved in water.strong acid when dissolved in water. E.g.:- Nacl(NaOH + HCl)E.g.:- Nacl(NaOH + HCl) E.g.:- NaE.g.:- Na22SOSO44(NaOH +H(NaOH +H22SOSO44))

E.g.:- KNOE.g.:- KNO33 ( KOH + HNO ( KOH + HNO33))

SALTS OF A STRONG ACID AND WEAK BASE

– They are acidic with a pH value less than 7.– These salts produce a strong acid and a weak

base when dissolved in water.

– E.g. :- NH4Cl(NH4OH + HCl)

SALTS SALTS OFOF A A WEAKWEAK ACID ACID ANDAND STRONG STRONG BASEBASE

They are basic in nature, with a pH value They are basic in nature, with a pH value more than 7.more than 7.

These salts produce a strong base and These salts produce a strong base and weak acid when dissolved in water.weak acid when dissolved in water.

E.g.:- NaE.g.:- Na22COCO33 (NaOH + H (NaOH + H22COCO33))

Common SaltCommon Salt

It acts as a raw material for various It acts as a raw material for various materials of daily use, such as:-materials of daily use, such as:-

1.1. NaOH (caustic Soda)NaOH (caustic Soda)

2.2. NaHCONaHCO33(Baking Soda)(Baking Soda)

3.3. NaNa22COCO33(Washing Soda)(Washing Soda)

4.4. CaOClCaOCl22(Bleaching powder)(Bleaching powder)

Preparing NaOH from NaCl

• This is how you prepare NaOH from NaCl• NaOH is prepared by passing electricity trough an

aqueous solution of NaCl (called brine). This process is called CHLOR-ALKALI process ( chlor for chlorine and alkali for sodium hydroxide –an alkali). During the process , NaCl decomposes to form

• (i) Chlorine gas at anode.• (ii) Hydrogen gas at cathode.• (iii) NaOH near the cathode.

Preparing Bleaching powder from NaCl

• The chlorine gas produced during the chlor-alkali process is used for manufacturing bleaching powder by the action of chlorine gas on dry slaked lime.

Ca(OH)2 + Cl2 CaOCl2 + H2O

Uses of CaOCl2 :(i) For bleaching cotton, linen, wood pulp and washed

clothes in laundry.

(ii) As an oxidizing agent in chemical industries.(iii) For disinfecting water ( to make it germ free).

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Preparing baking soda from NaCl

• Baking soda is prepared by Solvay process using sodium chloride as one of the raw materials.

• NaCl + H2O + CO2 NH3 NH4Cl +NaHCO3

• THE USES OF Baking soda are:-• (i) fire extinguishers• (ii) in antacids , as it neutralizes excess acid in the

stomach.

• NaHCO3+ H+ CO2 + H2O +Sodium salt of an acid.

• (iii) For making baking powder (which is a mixture of NaHCO3 and mild edible acid like tartaric acid).

Preparing washing soda from NaCl• When NaHCO3 is decomposed, it forms Na2CO3 and when

Na2CO3 is re-crystallized it gives washing soda (basic salt)

• 2 NaHCO3 Na2CO3 + H2O + CO2

• Na2CO3 + 10 H2O Na2CO3.10H2O

• Uses of washing soda:-• (i) it is used in glass, soap and paper industry.• (ii) it is used for making borax.• (iii) it is used for removing permanent hardness.• (iv) it is used as a cleaning agent for domestic purposes.

Water of crystallization

• It means the number of water molecules needed for the formation of the crystals of any salt.

• Thus water of crystallization is the fixed amount of water molecules present in one salt formula.

• E.g.:- CuSO4.5H2O (It means 5 water molecules are present in one formula of CuSO4)

Plaster of parisPlaster of paris

• When• When