Question

(i) What happens when:
(a) Borax is heated strongly
(b) Boric acid is added to water
( c) Aluminium is treated with dilute `NaOH`.
(d) `BF_(3)` is reacted with ammonia.
(ii) Explain the following reaction.
`CO` is heated with `ZnO`.

Answer 1

Correct Answer - (i)(a)When borax is heated strongly, a transparent glassy bead which consists of sodium metaborate `(NaBO_(2))` and boric anhydride is formed.
`Na_(2)B_(4)O_(7). 10H_(2)Ooverset(Delta)toNa_(2)B_(4)O_(7)+10H_(2)O uar r`
`Na_(2)B_(4)O_(7)overset(740^(@)C)to 2NaBO_(2)+underset("borax bead")(B_(2)O_(3))`
(b)Boric act acts as a weak Lewis acid by accepting a hydroxide ion of water and releasing a proton into the solution.
( c)Dihydrogen is evolved.
`2Al(s)+2NaOH(aq)+6H_(2)O(l)to2Na^(+)[Al(OH)_(4)]^(-)(aq)+3H_(2)(g)`
(d)`BF_(3)` being a lewis acid accepts a pair of electrons from `NH_(3)` to form the corresponding complex.
(ii)`ZnO` is reduced to zinc metal.
`ZnO+CO to Zn+CO_(2)`