Hydrogen And Its Compounds Question 17
Question: Permanent hardness due to $ M{g^{2+}} $ ions is best removed by
Options:
A) $ Ca{{(OH)}_2} $
B) $ Na_2CO_3 $
C) $ Na_2CO_3+Ca{{(OH)}_2} $
D) None of these
Show Answer
Answer:
Correct Answer: C
Solution:
$ Ca{{(OH)}_2} $ removes the permanent hardness due to $ M{g^{2+}} $ ion, but it produces $ C{a^{2+}} $ ions which are removed by $ Na_2CO_3 $ . $ M{g^{2+}}+Ca{{(OH)}_2}\to Mg{{(OH)}_2}\downarrow +C{a^{2+}} $
$ C{a^{2+}}+Na_2CO_3\to CaCO_3\downarrow +2N{a^{+}} $
$ Ca{{(OH)}_2} $ or $ Na_2CO_3 $ alone cannot remove the permanent hardness.
BETA
