Question

The borax bead is chemically:
A. ${B_2}{O_3}$
B. $N{a_2}{B_4}{O_7}$
C. $N{a_3}B{O_3}$
D. ${B_2}{O_3} + NaB{O_2}$

Answer 1

Borax is an amorphous solid, white in color. It has been used as a cleaning agent for decades. It has many uses, it helps get rid of strains, mold, etc. Borax is also known as sodium tetraborate decahydrate, the formula is $N{a_2}\left[ {{B_4}{O_5}{{\left( {OH} \right)}_4}} \right]\cdot8{H_2}O$ .

Complete step by step answer:
When borax is heated, the flame borax swells up as it loses its water of crystallization. The borax bead is a mixture of boric oxide and sodium metaborate the reaction is shown below,
$N{a_2}{B_4}{O_7}.10{H_2}O\, \to N{a_2}{B_4}{O_7} + 10{H_2}O \to {B_2}{O_{3}}(boricoxide) + 2NaB{O_2}(sodium\,metaborate)$
Therefore, the borax bead is chemically is ${B_2}{O_3} + NaB{O_2}$
So, the correct answer is D.

Additional information:
Microcosmic salt, which is also known as stercorite. The salt exists as a white colored crystalline solid. It is formed by the reaction between sodium phosphate and ammonium phosphate. The chemical name for microcosmic salt is sodium ammonium phosphate and hence the chemical formula is $Na(N{H_4})HP{O_4}$ .
Also, when this salt is heated until it is red, it leaves a transparent glass of sodium phosphate. This compound dissolves in metal oxides like borax and results in the formation of glasses that have peculiar hues of colors. This method is also used in the qualitative analysis of various other substances and is known as the bead test. This name has been given to this process because of the formation of beads of sodium phosphate upon heating. the name of Microcosmic salt or sodium ammonium phosphate is derived from the word ‘microcosm’ because it is contained in the decomposing urine of a man.

Note: The borax bead test is a traditional part of qualitative analysis to test for the presence of many metals like manganese, cobalt, nickel, silver, etc. it is also known as the blister test. Cobalt makes the color of the bead blue. Nickel gives the yellow-brown in color etc. aluminum does not give borax bead test.