Colour of the bead in borax bead test is main | vedclass

Name: PDF Generator App | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

Borax on strong heating loses its water of crystallization and then shrinks forming a

transparent glassy bead of sodium metaborate $\left(\mathrm{N}

Vedclass · Accepted Answer

metal metaborates

Vedclass · Answer

Borax on strong heating loses its water of crystallization and then shrinks forming a

transparent glassy bead of sodium metaborate $\left(\mathrm{N} \mathrm{aB} \mathrm{O}_{2}\right)$ and boric anhydride $\left(\mathrm{B}_{2} \mathrm{O}_{3}\right)$ as shown

in reaction given below:

$\mathrm{Na}_{2} \mathrm{B}_{4} \mathrm{O}_{7} \cdot 10 \mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{Na}_{2} \mathrm{B}_{4} \mathrm{O}_{7}+10 \mathrm{H}_{2} \mathrm{O}$

$\mathrm{Na}_{2} \mathrm{B}_{4} \mathrm{O}_{7} \rightarrow 2 \mathrm{NaBO}_{2}+\mathrm{B}_{2} \mathrm{O}_{3}$

Boric anhydride, being non-volatile displaces more volatile acidic oxides and combine with basic oxides present to form metaborates which are identified through their characteristic colours.

Colour of the bead in borax bead test is mainly due to the formation of

Similar Questions

In the metallurgy of aluminium, cryolite is mixed in the molten state because it

The purification of alumina is called

Which of the following statements about anhydrous aluminium chloride is correct?

How can you explain higher stability of $BCl_3$ as compared to $TlCl_3$?

Identify the compounds $A, X$ and $Z$ in the following reactions :

$A + 2HCl + 5{H_2}O \to 2NaCl + X$

$X\xrightarrow[{370\,K}]{\Delta }HB{O_2}\xrightarrow[{ > 370\,K}]{\Delta }Z$