p-Block Elements – II — Chemistry STD 12 — Question
Tamilnadu BoardEnglish MediumSTD 12Chemistryp-Block Elements – II3 Marks
Question
How will you manufacture sulphuric acid by contact process?
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Answer
Manufacture of sulphuric acid by contact process involves the following steps:
$1.$ Initially sulphur dioxide is produced by burning sulphur or iron pyrites in oxygen/air.
$S + O _2 \rightarrow SO _2$
$4 FeS _2+11 O _2 \rightarrow 2 Fe _2 O _3+8 SO _2$
$2.$ Sulphur dioxide formed is oxidised to sulphur trioxide by air in the presence of a catalyst such as $V _2 O _5$ or platinised asbestos.
$3.$ The sulphur trioxide is absorbed in concentrated sulphuric acid and produces oleum $\left( H _2 S _2 O _7\right)$. The oleum is converted into sulphuric acid by diluting it with water.
$SO _3+ H _2 SO _4 \longrightarrow H _2 S _2 O _7 \stackrel{ H _2 O }{\longrightarrow} 2 H _2 SO _4^{\text { }}$
To maximise the yield the plant is operated at 2 bar pressure and $720 K$. The sulphuric acid obtained in this process is over $96 \%$ pure.
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