Sulfuric Acid

Sulfuric acid is also known as the oil of vitriol. Sulfuric acid is a mineral acid with elements sulfur,  oxygen and hydrogen. It has the molecular formula \(H_2SO_4\). Sulfuric acid is a colourless and viscous liquid. It is miscible with water at all concentrations.

Introduction to Sulfuric Acid

Sulfuric acid in its pure form is highly corrosive towards other materials. It is an oxidant and a strongly acidic nature and is highly dehydrating. Sulfuric acid strips water away from any substance when it comes into contact. Sulfuric acid is hygroscopic, it readily absorbs water vapour from the air. Upon adding sulfuric acid to water, a lot of heat is released. Upon contact, pure sulfuric acid can cause chemical burns and even thermal burns due to dehydration. The solution of sulfuric acid in water is less hazardous. The solution of the acid in water is very acidic, and should therefore be handled with care.

Sulfuric acid is an important commodity chemical. The production of sulfuric acid in a nation is a good indicator of its industrial strength. Sulfuric acid is widely synthesised with different methods, like the contact process, wet sulfuric acid process, lead chamber process and some other methods. Sulfuric acid is an important substance in the chemical industry. It is most commonly used in the manufacturing of fertilizer.

The Physical Properties of Sulfuric Acid

• The molecular weight or molar mass of Sulfuric acid is 98.079 gram per mole.
• The density of Sulfuric acid is 1.84 gram per centimetre cube.
• While the boiling point of Sulfuric acid is \(337^oC\).
• The melting point of Sulfuric acid is \(10^oC\).
• The vapour pressure of pure sulfuric acid is less than 0.001 mmHg at \(25^oC\) and 1 mmHg at \(145.8^oC\), and 98% sulfuric acid has vapour pressure is less than 1 mmHg at \(40^oC\).
• Anhydrous Sulfuric acid is a polar liquid. It has a dielectric constant of around 100.
• Sulfuric acid has a high electrical conductivity. It is due to dissociation through protonating itself, a process known as autoprotolysis.

The Chemical Properties of Sulfuric acid

• Being an acid, sulfuric acid easily reacts with most bases and give the corresponding sulphate. For instance, the blue copper salt copper(II) sulphate is commonly in use for electroplating and as a fungicide. It is done by the reaction of copper(II) oxide with sulfuric acid:

\(CuO (s) + H_2SO_4 (aq) \rightarrow CuSO_4 (aq) + H_2O (l)\)

• Sulfuric acid can displace weaker acids from their salts on reaction with sodium acetate. For example, displaces acetic acid and forms sodium bisulphate.

\(H_2SO_4 + CH_3COONa \rightarrow NaHSO_4 + CH_3COOH\)

• Dilute sulfuric acid reacts with many metals by a single displacement reaction as with other acids, producing hydrogen gas and salts. It attacks reactive metals like iron, aluminium, zinc, manganese,  magnesium, and nickel.

\(Fe + H_2SO_4 \rightarrow H_2 + FeSO_4\)

Uses of Sulfuric Acid

• In making fertilizers.
• In the production of steel and iron.
• To produce phosphoric acid.
• In chemical manufacturing industries.
• In petroleum refining.
• As a cleaning agent in industries to remove the rust from steel and iron.
• In storage batteries.
• As a catalyst to convert cyclohexanone oxime to caprolactam in use to make nylon.
• In lead-acid batteries as an electrolyte.
• In making ammonium sulphate.

FAQs on Sulfuric Acid

Question 1: Can you neutralize sulfuric acid with water?
Answer: If you have a certain amount of concentrated Sulfuric acid, one should pour it into a sodium hydroxide solution i.e., NaOH. The water will dilute and take off some heat that usually the sodium carbonate or bicarbonate produces when it neutralizes the acid.

Question 2:  What happens when Sulfuric acid reacts with carbon and sodium chloride?

Answer: In reaction with carbon, Sulfuric acid oxidizes carbon and sulfur.

\(S + 2 H_2SO_4 \rightarrow 3 SO_2 + 2 H_2O\)

Sulfuric acid reacts with sodium chloride and gives hydrogen chloride gas and sodium bisulphate.

\(NaCl + H_2SO_4 → NaHSO_4 + HCl\)