First slide

Uses of Boron & Aluminium

Question

Al₂O₃ formation from aluminium and oxygen involves evolution of a large quantity of heat, which makes aluminium useful in

Moderate

A

deoxidiser
B

confectionary
C

indoor photography
D

thermit welding

Solution

Alumino thermit reactions are exothermic chemical reactions and in these reactions aluminium is acting as the reducing agent at high temperatures.Due to the liberation of high heat energy the formed metal will be in melted form (in liquid state). Hence alumino thermic reactions have been used for welding of rail tracks.This is said to be thermite welding.
$eg.,\,\,\,F{e_2}{O_3} + \mathop {Al}\limits_{\operatorname{Re} ducing\,\,\,agent} \xrightarrow{{High\,\,temperature}}A{l_2}{O_3} + 2Fe + \mathop \Delta \limits_{Heat\,\,energy}$
In aluminothermite process "Al" acts as reducing agent .
→ " Al "acts as strong reducing agent.
eg.,
$C{r_2}{O_3} + 2Al\xrightarrow{{}}2Cr + A{l_2}{O_3}$
${B_2}{O_3} + 2Al\xrightarrow{{}}2B + A{l_2}{O_3}$
${Mn_3}{O_4} + 8Al\xrightarrow{{}}9Mn + 4A{l_2}{O_3}$
ALUMINO THERMITE PROCESS
Mixture of metal oxide and Al powder in 3:1 ratio is called Thermite mixture.
Mixture of BaO₂ and Mg or Al powder is called ignition mixture.
Example for thermite mixture is, Fe₂O₃ and Al 3:1 ratio.
→ On burning of Mg-ribbon, it carries the flame into ignition mixture.Ignition mixture on ignition provides huge amount of energy.By using this energy Al of thermite mixture reduces the metal oxide to metal. The metal obtained in this process will be in liquid state .This formed liquid metal (Fe) is used for welding of train rails and welding of other metals.

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App