Question

In the Borax Bead Test Which Of The Following Compounds Is Formed?

• A. Triborate
• B. Metaborate
• C. Orthoborate
• D. Tetraborate

Answer 1

The correct option is B

Metaborate

Explanation for the Correct Option:

Option (B):

• The borax bead test is used as the quantitative inorganic analysis for the detections of different cations such as iron, chromium, cobalt, copper, nickel, and manganese in the sample.
• Borax has chemical formula $\mathrm{N}{a}_2{\mathrm{B}}_4{\mathrm{O}}_7.10{\mathrm{H}}_2\mathrm{O}$ having the chemical name sodium pyroborate.
• On heating, borax loses its water of crystallization and swells to form the products as sodium tetraborate and ten molecules of water.
  $\mathrm{N}{\mathrm{a}}_2{\mathrm{B}}_4{\mathrm{O}}_7.10{\mathrm{H}}_2\mathrm{O}\stackrel{\mathrm{\Delta }}{\to }\mathrm{N}{\mathrm{a}}_2{\mathrm{B}}_4{\mathrm{O}}_7+10{\mathrm{H}}_2\mathrm{O}$
• The white porous mass thus obtained by additional heating melts to give a clear liquid which it undergoes solidification to a transparent glossy bead, giving the products of the reaction as boric anhydride and sodium metaborate.
  $\mathrm{N}{\mathrm{a}}_2{\mathrm{B}}_4{\mathrm{O}}_7\stackrel{\mathrm{\Delta }}{\to }{\mathrm{B}}_2{\mathrm{O}}_3+2\mathrm{NaB}{\mathrm{O}}_2$
• The bead thus formed is known as a borax bead which is used to detect colored radicals. The test is called the borax bead test.
• Hence the correct option is (B); Metaborate.

Explanation for the incorrect Options :

Option (A):

• Triborate is not formed as a product of borax bead test.
• Hence the given option does not coincide with the correct option.

Option (C):

• In the borax bead test experiment Orthoborate doesn't form as the final product.
• hence the given option is not the correct one.

Option (D):

• Tetraborate is not formed as a product of borax bead test.
• Hence, the given option does not represent the correct concept.

Hence the correct option is (B); Metaborate.