Question

The composition of thermite mixture is:
A. iron (III) oxide and aluminium powder in the ratio 1:3.
B. aluminium powder and iron (III) oxide in the ratio 1:3.
C. aluminium powder and barium peroxide in the ratio 1:3.
D. barium peroxide and aluminium powder in the ratio 1:3.

Answer 1

Hint: To solve this question, we have to remember that thermite mixture is a pyrotechnic composition of metal powder fuel and metal oxide. It has a diverse composition including Aluminium because of its high boiling point and low cost. Oxidizers include iron (III) oxide. This mixture is used for thermite welding, often used to join rail tracks, metal refining, weapons, fireworks etc.

Complete step by step answer:
Thermite is a mixture of an oxide of one metal and a powder of another metal. Aluminium is usually used as a metal that decreases the oxide of the metal.
e.g. iron thermite $\left( {F{e_2}{O_3} + Al} \right)$
        chromium thermite $\left( {C{r_2}{O_3} + Al} \right)$
        copper thermite $\left( {CuO + Al} \right)$
The thermite reaction requires metal oxide reduction by metal. In oxide shape, the metal should have a lower reduction potential than the metal. As it has a strong affinity for oxygen, aluminium is selected as a metal and its oxide $A{l_2}{O_3}$, is a highly exothermic compound.
The popular thermite contains a mass ratio of ferric oxide and aluminium of 3:1. It is used to weld broken iron pieces thermally. The reduction of aluminium ferric oxide is extremely exothermic, so the iron produced would be in the molten state.
  $F{e_2}{O_3} + 2Al \to A{l_2}{O_3} + 2Fe + heat$

Hence, we can say that thermite mixture is a composition of aluminium powder and iron (III) oxide in the ratio 1:3.
So, the correct answer is “Option B”.

Note: Goldschmidt aluminothermic reaction is also called thermite reaction involving aluminium. This reaction is normally caused by the burning of a magnesium ribbon in the presence of barium peroxide.
Thermite reactions are also used in chromium and manganese pyrometallurgy. Aluminium reduces chromium oxide to chromium in this procedure.
$C{r_2}{O_3} + 2Al \to A{l_2}{O_3} + 2Cr + heat$