C₁V₁ = C₂V₂

Where:

C₁: Concentration of the concentrated acid (in %)

V₁: Volume of the concentrated acid to be used

C₂: Desired concentration of the dilute acid (in %)

V₂: Volume of the dilute acid to be prepared

For example, to prepare 1 L of a 0.5 M H2SO4 solution from concentrated H2SO4 (18 M), the formula can be used as follows:

C₁ = 18 M (Concentration of the concentrated acid)

V₁ = ?

C₂ = 0.5 M (Desired concentration of the dilute acid)

V₂ = 1 L (Volume of the dilute acid to be prepared)

Rearranging and solving for V₁:

V₁ = (C₂V₂) / C₁ = (0.5 M * 1 L) / 18 M = 0.028 L or 28 mL

Therefore, 28 mL of the concentrated H2SO4 should be added to 972 mL of water to prepare 1 L of a 0.5 M H2SO4 solution.