‘Q. No. 11.Na2SO4 is a neutral salt while NaHSO4 is an acidic salt. Justify.
Answer. Na2SO4 is formed by the reaction of strong base NaOH with strong acid H2SO4. It is formed by the complete replacement of ionizable H+ ions of H2SO4. As Na2SO4 does’ not have replaceable H+ ions. It is a natural salt.
NaOH + H2SO4 Na2SO4 + H2O
While NaHS04 is formed by incomplete replacement of H+ off by a base:
H2S04 + NaOH ———> NaHSO4 + H2O
It further reacts with base to form normal salt:
NaHSO4(aq) + NaOH(aq) —————> Na2SO4(aq) + H2O
As NaHSO4 has one replaceable H+ ion. It can react with base so it is acidic salt.
- No.12. Give a few characteristic properties of salts.
Answer. Characteristic properties of salts are as follows
- . Salts are ionic compounds found in crystalline form.
- . They have high melting and boiling points.
(iii). Most of the salts contain water of crystallization which is responsible for the shape of the crystals. Numbers of molecules of water are specific for each salt and they are written with the chemical formula of a salt. For example,
Copper sulphate CuSO4.5H2O; Calcium sulphate CaSO4.2H2O
(iv) . Salts are neutral compounds. Although, they do not compose of equal number of positive and negative ions, but have equal number of positive and negative charges.
- No.13. How the soluble salts are recovered from water?
Answer. Soluble salts are recovered from water by evaporation or crystallization method. When salt .solution is evaporated, water vaporizes leaving behind salt.