Question

Borax bread test can be used for detection of

Answer 1

On heating ,borax loses water of crystallisation and swells up to form fluffy mass. On further heating it melts to give a clear liquid which solidifies to a transparent glossy bead consisting of sodium metaborate and boric unhydride.

Na2B4O7. 10H₂O—>Na₂B₄O7—>2NaBO₂ + B₂O₃

The bead is commonly known as borax bead and is used to detect coloured radicals under the name borax bead test. For example ,when borax is heated with CoO on loop of platinum wire,a blue coloured Co(BO₂)₂ bead is formed.

Answer 2

$\huge\mathcal\blue{Answer:}$

$\boxed{\red{\texttt{Borax\:bead\:test}}}$

Sodium tetaraborate decahydrate $\boxed{\green{Na_2B_4O_7.10H_2O}}$is called borax

On heating borax first it swells up due to the elimination of the water molecules. On further heating it melts to a liquid which then solidifies to a transparent glassy mass. It contains sodium meta borate and boric acid

$\red{Na_2B_4O_710H_2O}{\rightarrow}\blue{Na_2B_4O_7}{\rightarrow}\pink{2NaBO_2+B_2O_3}$

${B_2O_3}$ combines with meat oxides to form metal metaborates which form coloured beads. This reaction is called " Borax bead test"

$\blue{B_2O_3+CoO}{\rightarrow}\pink{Co(BO_2)_2}$