Question

Cu salts give which coloured borax bead test in reducing flame

Answer 1

in reducing flame cupric metaborate is reduced to mettalic copper which is red and opaque

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"

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