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. H2SO4 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.


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. 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.
Na2B4O7+7H2Owater2 NaOH+  4H3BO3Borax(X)             Sodium hydroxide   Orthoboric acid Na2B4O7.10H2ONa2B4O7B2O3+2NaBO2Borax(X)          Sodium metaborate   Boric anhydride(Glassy material)
When concentrated acid is added to borax, white crystals of orthoboric acid (Z) are formed.
Na2B4O7.10H2O+H2SO4Na2SO4+4H3BO3+5H2O  Borax(X)                               Orthoboric acid(Z)