Question 11.30 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.
Class XI The p-Block Elements Page 325
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(i) Aqueous solution of salt X is alkaline . it means that 'X' is the salt of strong base (alkaline) and weak acid .
e.g., Na2B4O7.10H2O(X) --(water)---->2NaOH (strong base ) + H2B4O7 (weak acid) + 8H2O
(ii) by strong heating of salt X , it swells up to a glassy material Y . it means that the salt 'X' is Borax.
e.g., Na2B4O7 -----∆------>{ 2NaBO2 + B2O3}glassy beads , Y
(iii) reaction between Hot aqueous solution of Borax and conc.H2SO4 gives crystal of orthoboric acid.
e.g., Na2B4O7.10H2O + H2SO4 -------> 4H3BO3 (orthoboric acid, Z) + Na2SO4 + 5H2O
e.g., Na2B4O7.10H2O(X) --(water)---->2NaOH (strong base ) + H2B4O7 (weak acid) + 8H2O
(ii) by strong heating of salt X , it swells up to a glassy material Y . it means that the salt 'X' is Borax.
e.g., Na2B4O7 -----∆------>{ 2NaBO2 + B2O3}glassy beads , Y
(iii) reaction between Hot aqueous solution of Borax and conc.H2SO4 gives crystal of orthoboric acid.
e.g., Na2B4O7.10H2O + H2SO4 -------> 4H3BO3 (orthoboric acid, Z) + Na2SO4 + 5H2O
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