Difference Between Sulphuric Acid and Hydrochloric Acid

Sulphuric Acid vs Hydrochloric Acid
 

We normally identify an acid as a proton donor. Acids have a sour taste. Lime juice and vinegar are two acids we come across at our homes. They react with bases producing water, and they react with metals to form H₂; thus, increase metal corrosion rate. Acids can be categorized into two, based on their ability to dissociate and produce protons. Strong acids are completely ionized in a solution to give protons. Weak acids are partially dissociates and give fewer amounts of protons. K_a is the acid dissociation constant. It gives an indication of the ability to lose a proton of a weak acid. To check whether a substance is an acid or not we can use several indicators like litmus paper or pH paper. In the pH scale, from 1-6 acids are represented. An acid with pH 1 is said to be very strong, and as the pH value increases, acidity decreases. Moreover, acids turn blue litmus to red. All the acids can be divided into two as organic acids and inorganic acids depending on their structure. Sulphuric acid and hydrochloric acid are commonly used strong inorganic acids. These are also known as mineral acids, and they are derived from mineral sources. Inorganic acids release protons when dissolved in water.

Sulphuric Acid

The molecular formula of sulphuric acid is H₂SO₄. Sulfur is the central atom of the molecule and has bonded to two OH groups and two oxygens (with double bonds). Molecule is tetrahedrally arranged. Sulphuric is strong, corrosive and a viscous liquid. It is a very polar liquid with a large dielectric constant and readily soluble in water. The ionization reaction of sulphuric is as follows.

H₂SO₄  → HSO₄ ^– + H⁺

HSO₄ ^–  →  SO₄ ^2- + H⁺

Sulphuric acid is a powerful proton donor; therefore, in a solution it completely dissociates and gives two protons. It is a moderately strong oxidizing agent. Since sulfur is in +6 oxidation state (which is the highest oxidation state for sulfur), it can undergo reduction to +4 state and acts as an oxidizing agent. In dilute solutions, sulphuric can form two slats, bisulfate salt and the sulfate salt. Sulphuric can also act as a dehydrating agent: thus, used in organic condensation reactions like esterification.

Hydrochloric Acid

Hydrochloric acid, denoted as HCl, is a mineral acid, which is very strong and highly corrosive. This is a colorless, nonflammable liquid. It is stable, but readily reacts with bases and metals. It has the capability to ionize and donate only one proton. Following is the dissociation reaction of HCl in aqueous medium.

HCl +H₂O → H₃O⁺ + Cl^–

As it is a strong acid, the acid dissociation constant of HCl is very large. HCl is used in fertilizer, rubber, textile and dye manufacturing industries. And it is a widely used acid in laboratories for base titrations, or to provide acidic media, or to neutralize basic solutions, etc.