Question

In a solution of H2SO4, rank the concentration of H2SO4, H+, SO42- from highest concentration to lowest concentration.

Answer 1

Answer:

• [H⁺] > [SO₄²⁻] > [H₂SO₄]

Explanation:

H₂SO₄ is a strong acid, which means that most of it ionizes in aqueous solution.

Since it is a diprotic acid (two hydrogen ions) its ionization occurs in two steps:

• H₂SO₄ (aq) → H⁺(aq) + HSO₄⁻(aq)

• HSO₄⁻ (aq) → H⁺(aq) + SO₄²⁻(aq)

Thus, almost all H₂SO₄ has ionized and its final concentration is almost nothing.

After the first ionization, the conentrations of H⁺(aq) and HSO₄⁻ are equal but by the second ionization more H⁺ ions are produced along with SO₄⁻.

You can show it as one step dissociation, assuming 100% dissociation (given this is a strong acid):

By the stequiometry you can build this table:

                 H₂SO₄ (aq) → 2H⁺(aq) + SO₄²⁻(aq)

Initial                A                 0              0

Change           - x               +2x          +x

Equilibrium       A - x           2x             x

As explained, A - x is very low, and 2x is twice x. Thus,

The rank of the concentrations from highest to lowest is:

• [H⁺] > [SO₄²⁻] > [H₂SO₄]