- 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)
- They turn blue litmus red.
- They react with bases to form normal salts.
- No.7. Give four uses of calcium oxide.
- It is used as drying agent for gases and alcohol
- It is used in steel making, water treatment and other chemicals like slaked lime, bleaching powder, calcium carbide.
- It is used for purification of sugar
- A mixture of CaO and NaOH called soda lime is used to remove carbon dioxide and water vapours from atmosphere.
- No.8. You are having a strong acid (HNO3) and strong base (NaOH) on mixing;
- What type of salt you will have?
- What type of this reaction will be?
iii. Will it be soluble or insoluble?
- If it is soluble, how it will be recovered?
It can be explained by taking example of HNO3 (strong acid) and NaOH (strong base).
- It will form normal salt
- The type of reaction is neutralization reaction
iii. The salt will be soluble
- As salt is soluble, it is recovered by evaporation or crystallization
- No.9. Explain why:
- HCl forms only one series of salts,
- H2SO4 forms two series of salts.
iii. H3PO4 forms three series of salts.
Give necessary equations.
Formation of series of salts depends upon number of replaceable H+ ions in an acid.
- As HC1 has only one replaceable H+ ion, it forms one series of salts.
HCl2(aq) + KOH(aq) ————— KHSO4(aq) + H2O(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)