Question

${{H}_{3}}B{{O}_{3}}\xrightarrow{{{T}_{1}}}X\xrightarrow{{{T}_{2}}} Y \xrightarrow{redhot}{{B}_{2}}{{O}_{3}}$ if ${{T}_{1}}<{{T}_{2}}$ then X and Y respectively are:
a.) X = Meta boric acid and Y = Tetra boric acid
b.) X = Tetra boric acid and Y = Meta boric acid
c.) X = Borax and Y = Meta boric acid
d.) X = Tetra boric acid and Y = Borax

Answer 1

Hint: When boric acid is strongly heated, at about $120^o $C, it dehydrates and converts further to form its polymers. Boric acid is an extracted, processed, and refined form of borax, found in a variety of chemical products.

Complete Solution :
- Boron is naturally present everywhere on the earth, including in rocks, soils, and natural waters. However, large borate mineral deposits are rare.
- When boric acid is strongly heated, it dehydrates forming its polymer, meta boric acid.
- On further heating, meta boric acid breaks up to form It converts to form boron trioxide.
- This can be explained by the chemical reaction given below
     \[{{H}_{3}}B{{O}_{3}}\xrightarrow{{{100}^{0}}C}HB{{O}_{2}}\xrightarrow{{{160}^{0}}C}{{H}_{2}}{{B}_{4}}{{O}_{7}}\xrightarrow{redhot}{{B}_{2}}{{O}_{3}}\]
So, X is $HB{{O}_{2}}$, Meta boric acid and Y is ${{H}_{2}}{{B}_{4}}{{O}_{7}}$, Tetra boric acid.
So, the correct answer is “Option A”.

Additional Information. Borates have many industrial uses. The largest one is the manufacture of glass, including energy saving insulation fiberglass and borosilicate glasses. Other uses include the manufacture of ceramics, building products, house wares, consumer electronics, fertilizers, alloys, magnets, lubricants, and adhesives.

Note: Boric acid is a weakly acidic hydrate of boric oxide with mild antiseptic, antifungal, and antiviral properties. It is often used to treat yeast infections and cold sores.