8d.1.4. Step 4

1. Burning sulfur or sulfide ores to form SO₂

In this step, sulfur (a non-metallic element) or sulfide ores, which are natural mineral forms of sulfur, are burned. Burning means that the sulfur reacts with oxygen in the air. When sulfur reacts with oxygen, it produces sulfur dioxide (SO₂) gas. This is the first reaction in the commercial production of sulfuric acid.

Think of this step like lighting a candle. When the wax (sulfur) burns in the presence of air (oxygen), it releases smoke (sulfur dioxide). Just like the smoke is a product of burning the candle, the SO₂ gas is a product of burning sulfur.

2. Oxidation of SO₂ to SO₃ using V₂O₅ catalyst: 2SO₂+O₂→V₂O₅ 2SO₃

In this step, the sulfur dioxide (SO₂) gas produced in the first step is further processed to make sulfur trioxide (SO₃). This is done by adding more oxygen (O₂) in the presence of a catalyst, which is vanadium pentoxide (V₂O₅). A catalyst is a substance that speeds up a chemical reaction without being consumed in the process. The reaction converts the SO₂ gas and oxygen into SO₃ gas.

This is similar to how a chef might use a special ingredient to speed up the cooking process. Just as the chef’s ingredient helps the food cook faster without itself becoming part of the meal, the V₂O₅ catalyst speeds up the conversion of SO₂ to SO₃ without being used up.

3. Absorption of SO₃ in concentrated H₂SO₄ to form oleum

Next, the sulfur trioxide (SO₃) gas is absorbed into concentrated sulfuric acid (H₂SO₄). This process leads to the formation of a substance called oleum. Oleum is a thick, oily liquid that contains dissolved SO₃ in sulfuric acid. This step is crucial because it allows for the safe handling of SO₃, which can be corrosive and hazardous. When SO₃ comes into contact with water, it can create a lot of heat and even cause acid fumes.

Imagine mixing sugar with syrup. The sugar (SO₃) is absorbed by the syrup (concentrated sulfuric acid) to create a thick mixture (oleum). Just like you can control the sweetness by adjusting how much sugar you add, here the amount of SO₃ controlled by how we manage the reaction process.

4. Dilution of oleum with water to get H₂SO₄

In the final step, oleum is diluted with water to produce sulfuric acid (H₂SO₄). Care must be taken when adding water to oleum because the reaction is highly exothermic, which means it releases a lot of heat. This heat could potentially cause the mixture to splatter or produce dangerous fumes if not handled correctly. Thus, it’s important to add oleum to water slowly and carefully.

This process is like making a strong juice concentrate and then adding water to dilute it to your preference. Just as you have to be careful about how much water you add, and how fast you do it, the same caution is needed when diluting oleum to prevent accidents.

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