Sulphuric Acid

You must have come across a lot of experiments with sulphuric acid. Haven’t you? So, is it ever put it in the water? NO! Never ever! But why? Let’s find out. In the following section, we will read all about sulphuric acid and its properties. After that, we will look at its uses. So let us first start with what it is.

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What is Sulphuric Acid?

Sulphuric acid also spelt as sulfuric acid or H₂SO₄ is an odourless, colourless, oily liquid. Also, it is very corrosive. Another name for it is Oil of Vitriol. On account of its wide applications, it has alluded as the ‘King of Chemicals’. Moreover, we can find it in both combined and free state.

Browse more Topics under The P Block Elements

• Introduction to p Block Elements
• Some Important Compounds of Carbon and Silicon
• Trend and Anomalous Properties of Carbon
• Trends and Properties of Boron and Aluminium
• Ammonia
• Chlorine
• Dinitrogen
• Dioxygen
• Boron Family: Group 13 Elements
• Carbon Family: Group 14 Elements
• The Group 15 Elements
• Group 16 Elements
• The Group 17 Elements
• Group 18 Elements
• Hydrogen Chloride
• Interhalogen Compounds
• Nitric Acid and Oxides of Nitrogen
• Oxoacids of Halogens
• The Oxoacids of Phosphorus
• Oxoacids of Sulphur
• Ozone
• Phosphine
• Phosphorus – Allotropic Forms
• Phosphorus Halides
• Simple Oxides
• Sulphur – Allotropic Forms
• Sulfuric Dioxide

Manufacturing Process of Sulphuric Acid

In general, there are two techniques for industrial production of sulfuric acid. They are:

• Lead chamber process
• Contact process

Now, let us look at these processes in detail.

1) Contact Process

The contact process has three major steps.

• Step – I: Production of Sulphur Dioxide

Sulphur dioxide is produced by heating sulphur or sulphide ores. For example, iron pyrites in excess of air.

S (Sulphur)   +   O₂(Oxygen)   +   Δ(Heating)    →    SO₂(Sulphur dioxide)

4FeS(Iron pyrites)   +   7O₂(Oxygen)   +   Δ(heating)    →    2Fe₂O₃(Ferric Oxide)  +  4SO₂(Sulphur dioxide)

• Step -II: Formation of Sulphur Trioxide

Then sulphur dioxide is oxidized with atmospheric oxygen to sulphur trioxide by using V₂O₅ as a catalyst.

2SO₂(Sulphur dioxide)   +   O₂(Oxygen)   +   V₂O₅(Catalyst)   →    SO₃(Sulphur trioxide)

• Step -III: Conversion of Sulphur Trioxide into Sulphuric Acid
  

After that, the sulphur trioxide is broken in 98% sulfuric acid to give oleum. Another name for oleum is pyrosulfuric acid. Then  Oleum is diluted with water to give sulfuric acid of the desired concentration.

SO₃(Sulphur trioxide)   +  H₂SO₄(Sulfuric acid-98%)    →    H₂S₂O₇(Pyrosulfuric acid/Oleum)

H₂S₂O₇(Pyrosulfuric acid/Oleum)    +  H₂O(Dilution)    →     2H₂SO₄(Sulfuric acid)

2) Lead Chamber Process

The lead Chamber process is one of the most common manufacturing techniques. It results in around 50-60 B grade acids. In this process, we use wet SO₂ in the presence of nitrogenous oxides (dynamic impetus). As a result, it gets oxidised with the oxygen in the air and forms sulphur trioxide. This reaction is expressed as

2SO₂   +   O₂    →   2SO₃

Then sulphur trioxide is made to react with water to get H₂SO₄. This reaction is expressed as

SO₃   +   H₂O   →    H₂SO₄

Physical Properties of Sulphuric Acid

• Sulfuric acid is a thick, colourless and an oily fluid.
• It has a specific gravity of 1.84 at 298 K.
• The boiling point of the acid is 611 K. The higher boiling point and thickness of this chemical is due to hydrogen bonding.
• This strong chemical reacts with water vigorously releasing quite a lot of heat. Thus, you must never add water to H₂SO₄. Instead, you should add the acid to water, slowly with proper stirring.

Chemical Properties of Sulphuric Acid

• Sulfuric acid is a strong dibasic acid. Also, it is diprotic and ionises in two stages in the aqueous solution.
• This chemical is highly corrosive, reactive and is soluble in water. It has a very high oxidising power and thus, acts as a strong oxidising agent.
• It has very low volatility. For this reason, it plays a part in the preparation of more volatile acids from their comparing salts.
• Concentrated sulfuric acid is a very strong dehydrating agent. Thus, this chemical is used for drying many wet gases which do not react with the acid.
• It additionally expels water from natural mixes like starches.
• As it is a good oxidising agent, it can oxidise both non-metals as well as metals. Moreover, it itself reduces to sulphur dioxide.

Some Common Reactions of Sulphuric Acid

• Hot concentrated sulfuric acid oxidizes copper to copper sulfate.

Cu   +    2H₂SO₄  →    CuSO₄  +   SO₂   +   H₂O

• Concentrated sulfuric acid gives out hydrogen chloride from sodium chloride. Also, it gives out hydrogen fluoride from calcium fluoride.

CaF₂    +   H₂SO₄  →     CaSO₄   +  2HF

• It burns glucose, sugar, and starch to carbon.

C₁₂H₂₂O₁₁   +   (H₂SO₄)    →  12C   +  11H₂O

Solved Example for You

Q: Write down the main uses of sulfuric acid.

Ans: The uses of sulfuric acid are:

• It is a common chemical in the preparation of fertilizers. For example, ammonium sulfate and superphosphate.
• We use it in the manufacture of dyes, shades, and paints.
• It is a common chemical in the manufacture of explosives. For example, TNT.
• Other imperative chemicals need the presence of sulfuric acid. Without sulfuric acid, we cannot get these chemicals. For example, hydrochloric, phosphoric and nitric acid. It is also needed for sodium carbonate.
• We utilise it as a part of the refining of petroleum.
• It acts as a pickling agent.
• This chemical is common as a laboratory agent, dehydrating agent and an oxidizing.