How acidic salts can be prepared. Give the Characteristics of an acidic salt.

 

  1. No. 6.   How   acidic   salts can   be prepared.   Give   the Characteristics of an acidic salt.

Answer. These salts are formed by partial replacement of replaceable H+ ions of an acid by a positive metal ion. For example,

H2SO4(aq) + KOH(aq) —————> KHSO4(aq) +(1)

H3PO4(aq) + NaOH(aq) —————NaH2PO4(aq) + H2O(1)

Characteristics

  1. They turn blue litmus red.
  2. They react with bases to form normal salts.
  1. No.7. Give four uses of calcium oxide.

Answer.

  1. It is used as drying agent for gases and alcohol
  2. It is used in steel making, water treatment and other chemicals like slaked lime, bleaching powder, calcium carbide.
  3. It is used for purification of sugar
  4. A mixture of CaO and NaOH called soda lime is used to remove carbon dioxide and water vapours from atmosphere.
  1. No.8. You are having a strong acid (HNO3) and strong base (NaOH) on mixing;
  2. What type of salt you will have?
  3. What type of this reaction will be?

iii.     Will it be soluble or insoluble?

  1. If it is soluble, how it will be recovered?

Answer.

It can be explained by taking example of HNO3 (strong acid) and NaOH (strong base).

  1. It will form normal salt
  2. The type of reaction is neutralization reaction

iii. The salt will be soluble

  1. As salt is soluble, it is recovered by evaporation or crystallization
  1. No.9. Explain why:
  2. HCl forms only one series of salts,
  3. H2SO4 forms two series of salts.

iii.     H3PO4 forms three series of salts.

Give necessary equations.

Answer.

Formation of series of salts depends upon number of replaceable H+ ions in an acid.

  1. As HC1 has only one replaceable H+ ion, it forms one series of salts.

HCl2(aq) + KOH(aq)  —————  KHSO4(aq) + H2O(1)

  1. As H2SO4 has two replaceable H+, ions, it forms two series of salts.

H2S04(aq) + KOH(aq) —————> KHS04(aq) + H2O(1)

KHSO4(aq) + KOH(aq) —————> K2SO4(aq) + H2O(1)

iii.      H3PO4has three replicable H+ ions, it forms three series of salts.

H3PO4(aq) + KOH(aq)   —————>  KH2PO4(aq) + H2O(1)

KH2PO4(aq) + KOH(aq) —————>   K2HPO4(aq) + H2O(1)

K2HPO4(aq) + KOH(aq) ———> K3PO4(aq) + H2O(1)

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