Question

Borax bead test is used to identify the nature of cation present in solution by observing the colour of the bead. The colour and bead of copper formed during its borax bead test in a hot oxidising flame is

Answer 1

• Borax bead test is used to identify the nature of cation present in solution by observing the color of the bead. The color and bead of copper formed during its borax bead test in a hot oxidizing flame is Green when hot and blue when cold.
• The compound boric anhydride is not flammable.
• It creates a distinctively colored metal metaborate bead when it reacts with a colored red metallic salt.
• Borax fuses and loses its crystallization water when heated.
• Boric anhydride and sodium metaborate are combined to make a clear, translucent glass bead, which swells into a fluffy, white, porous mass and melts into a colorless liquid.
• The compound boric anhydride is not flammable. It produces a distinctively colored metal metaborate bead when it reacts with colored metallic salt.
• While borax and $\mathrm{Cu}$ are heated, the colored metaborate $\mathrm{Cu}{({\mathrm{BO}}_2)}_2$ that results is green when hot and blue when cold.
• The chemical reaction can be depicted as:

$$\begin{gathered} {\mathrm{CuSO}}_4\left(\mathrm{aq}\right)\stackrel{∆}{\to }\mathrm{CuO}\left(\mathrm{s}\right)+{\mathrm{SO}}_3\left(\mathrm{g}\right) \\ \mathrm{CuO}\left(\mathrm{s}\right)+{\mathrm{B}}_2{\mathrm{O}}_3\left(\mathrm{s}\right)\to \mathrm{Cu}{\left({\mathrm{BO}}_2\right)}_2 \\ \mathrm{Cupric}\mathrm{metaborate} \end{gathered}$$