A certain salt X, gives the following results. (i) Its aqueous solution is alkaline to litmus. (ii) It swells up to a glassy material Y on strong heating (iii) When conc. H_2SO_4 is added to a hot solution of X, white crystal of an acid Z separates out. Write equations for all the above reactions and identify X, Y and Z.

A certain salt X, gives the following results. (i) Its aqueous soluti

1.	A certain salt X, gives the following results. (i) Its aqueous solution is alkaline to litmus. (ii) It swells up to a glassy material Y on strong heating (iii) When conc. H_2SO_4 is added to a hot solution of X, white crystal of an acid Z separates out. Write equations for all the above reactions and identify X, Y and Z.
Answer» Solution : (i) The given salt is alkaline to litmus. Therefore, X is a salt of a STRONG base and a weak acid. Also, when X is strongly heated, it swells to FORM substance Y. Therefore, X MUST be borax. `underset"(X)"(Na_2B_4O_7). 10H_2O overset(H_2O) tounderset"(Strong base)"(2NaOH) + underset"(Weak acid)"(H_2B_4O_7)` (ii) When borax is heated, it loses WATER and swells to form sodium metaborate. When heating is continued, it solidifies to form a glassy material Y. Hence, Y must be a mixture of sodium metaborate and boric anhydride. `Na_2B_4O_7 . 10H_2O overset(Delta)to Na_2B_4O_7 + 10 H_2O` `Na_2B_4O_7 OVERSETDELTATO ubrace(2NaBO_2+B_2O_3)_((Y))` (iii)When concentrated acid is added to borax, white crystals of orthoboric acid (Z) are formed. `Na_2B_4O_7. 10H_2O + H_2SO_4 to underset"(Z)"(4H_3BO_3) + 5H_2O + Na_2SO_4`