Elements of Groups 16, 17 and 18 — Chemistry STD 12 Science — Question
Maharashtra BoardEnglish MediumSTD 12 ScienceChemistryElements of Groups 16, 17 and 183 Marks
Question
How is dioxygen manufactured on a large scale?
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Answer
Dioxygen on a large scale or commercial scale is obtained by two following methods :
$(1)$ From water : By electrolysis of acidified water, $H _2$ gas is obtained at the cathode and $O _2$ is obtained at anode.
$H _2 O$ (acidified) $\stackrel{\text { dil. } H _2 SO _4}{\rightleftharpoons} H ^{+}+ OH ^{-}$
At cathode : $2 H ^{+}+2 e ^{-} \longrightarrow H _{2( g )}$
At anode : $2 OH ^{-} \longrightarrow \frac{1}{2} O _{2( g )}+ H _2+2 e ^{-}$
$(2)$ From air :
Carbon dioxide and water vapour is removed from air and the remaining gases are liquefied.
$O_2$ on large scale is obtained by fractional distillation of liquid air.
On distillation, liquid dinitrogen having low boiling point distils out first leaving behind liquid dioxygen. Then liquid $O_2$ is distilled out and separated.
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