Salts By Rohit Pratti

Table Of contents Categories of salts (a) Salts of a strong acid and a strong base (b) Salts of a strong acid and weak base (c) Salts of a strong base and weak acid Common Salt Preparing NaOH from NaCl Preparing Bleaching powder from NaCl Preparing Baking Soda from NaCl Preparing washing soda from NaCl Water of crystallization Plaster of Paris Salts

Salts Salts are the ionic compounds formed by the combination of positive charge (A.K.A cation) and the negative charge (A.K.A anion). Salts are electrically neutral. Generally, the positive is a metal ion excepting ammonium ion (NH4+) which is a non metallic ion.

Categories of Salt There are three categories of salt they are:- Salts of a strong acid and a strong base Salts of strong base weak acid Salts of strong acid and weak base.

Salts of a Strong Acid and strong base They are neutral with a pH value of 7. These salts produce a strong base and strong acid when dissolved in water. E.g.:- Nacl(NaOH + HCl) E.g.:- Na2SO4(NaOH +H2SO4) E.g.:- KNO3 ( KOH + HNO3)

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 OF A WEAK ACID AND STRONG BASE They are basic in nature, with a pH value more than 7. These salts produce a strong base and weak acid when dissolved in water. E.g.:- Na2CO3 (NaOH + H2CO3)

Common Salt It acts as a raw material for various materials of daily use, such as:- NaOH (caustic Soda) NaHCO3(Baking Soda) Na2CO3(Washing Soda) CaOCl2(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 : For bleaching cotton, linen, wood pulp and washed clothes in laundry. As an oxidizing agent in chemical industries. For disinfecting water ( to make it germ free).

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 paris When