How is sulphuric acid prepared by contact process ? Explain in short.
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Answer:
Contact process, modern industrial method of producing sulfuric acid; it has largely replaced the chamber, orlead-chamber, process. ... Sulfur dioxide and oxygen, passed over a hot catalyst, unite to form sulfur trioxide, which in turn combines with water to make sulfuric acid.
Steps involved in the manufacturing of sulphuric acid are as stated below:
Preparation of sulphur dioxide.
Conversion of sulphur dioxide into sulphur trioxide.
Conversion of sulphur trioxide formed into concentrated H2SO4.
Sulphuric acid - Contact Process
Step 1: Preparation of sulphur dioxide:
SO2 is prepared by burning sulphur in the presence of excess air so that the product combines with oxygen which is helpful for the next stage.
S(s) + O2 (g) → SO2(g)
Step 2: Preparation of sulphur trioxide:
Sulphur trioxide is formed when sulphur dioxide reacts with oxygen in a ratio of 1:1 at a temperature of 400 °C – 450°C and a pressure of 1-2 atm in the presence of V2O5 as a catalyst. This reaction is reversible in nature.
2SO2(g) + O2(g) ⇌ 2SO3(g)
Step 3: Preparation of concentrated sulphuric acid:
The sulphur trioxide formed is first made to react with concentrated sulphuric acid. Sulphur trioxide cannot be dissolved in water directly as it leads to the formation of fog. The product obtained after this reaction is known as oleum. The oleum obtained is then dissolved in water to obtain concentrated sulphuric acid.
H2SO4 + SO3(g) → H2S2O7(l)
H2S2O7(l) + H2O(l) → 2H2SO4