First slide

Borax

Question

Borax bead test is not given by

Easy

A

Aluminium salt
B

Cobalt salt
C

Copper salt
D

Nickel salt

Solution

When small amount of Borax is taken in pt loop and heated strongly then it turned to "Transparent glassy bead" (TPGB).For this transparent glassy bead add small quantity of unknown transition metal salt and heated again.Then it gives specified colour to the transparent glassy bead.The colour is due to the formation of respective transition metal meta borate.Based on the colour of TPGB we can detect the transition metal present in the unknown transition metal salt.
$\therefore$ This test is used to detect the transition metal present in the salt qualitatively.
$N{a_2}{B_4}{O_7}.10{H_2}O\xrightarrow{\Delta }N{a_2}{B_4}{O_7} + 10{H_2}O$
$N{a_2}{B_4}{O_7}\xrightarrow{{Strong\,heating}}\underbrace {\mathop {{B_2}{O_3}}\limits_{Boric\,\,anhydride} + \mathop {2NaB{O_2}}\limits_{Sodium\,\,metaborate} }_{T.P.G.B}$
$eg.,$
$\mathop {{B_2}{O_3}}\limits_{Boric\,\,anhydride} + CrO \to \mathop {Cr{{\left( {B{O_2}} \right)}_2}}\limits_{Green} Chromium\,\,metaborate\$
$\mathop {{B_2}{O_3}}\limits_{Boric\,\,anhydride} + MnO \to \mathop {Mn{{\left( {B{O_2}} \right)}_2}}\limits_{Pink} Manganese\,\,metaborate$ $\mathop {{B_2}{O_3}}\limits_{Boric\,\,anhydride} + FeO \to \mathop {Fe{{\left( {B{O_2}} \right)}_2}}\limits_{Green} Iron\,\,metaborate$ $\mathop {{B_2}{O_3}}\limits_{Boric\,\,anhydride} + CoO \to \mathop {Co{{\left( {B{O_2}} \right)}_2}}\limits_{Blue} Cobalt\,metaborate$
$\begin{gathered} \mathop {{B_2}{O_3}}\limits_{Boric\,\,anhydride} + NiO \to \mathop {Ni{{\left( {B{O_2}} \right)}_2}}\limits_{Brown} Nickel\,\,metaborate \\\ \mathop {{B_2}{O_3}}\limits_{Boric\,\,anhydride} + CuO \to \mathop {Cu{{\left( {B{O_2}} \right)}_2}}\limits_{Blue} Copper\,\,metaborate \\\ \end{gathered}$
Hint: GPGB³

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