Which is stronger sulphuric acid and phosphoric acid?

Which is stronger between sulphuric acid and phosphoric acid?

Why is one of them considered stronger than the other?

Answer:

Sulfuric acid is stronger than phosphoric acid due to its greater electronegativity and better ability to ionize and donate its H⁺ ions.

Sulfuric acid (H₂SO₄) and phosphoric acid (H₃PO₄) are both important acids, but when it comes to strength, sulfuric acid takes the lead. This is because of several key factors:

Electronegativity:

Electronegativity is the ability of an atom to attract shared electrons in a chemical bond. Sulfur, the central atom in sulfuric acid, has a higher electronegativity compared to phosphorus in phosphoric acid. This means sulfur is more effective in pulling electron density towards itself, making the hydrogen atoms in sulfuric acid more likely to ionize and release H⁺ ions, resulting in a stronger acid.

Ionization:

Sulfuric acid is a diprotic acid, meaning it can donate two protons (H⁺ ions) per molecule. Phosphoric acid, on the other hand, is a triprotic acid but only the first two protons are readily ionized. The third hydrogen in phosphoric acid is not as easily released due to the stronger P-H bond, making phosphoric acid less acidic compared to sulfuric acid.

In conclusion, the combination of higher electronegativity and more efficient ionization makes sulfuric acid a stronger acid when compared to phosphoric acid.