How is the concentration of hydronium ions (H3O+) affected when a solution of an acid is diluted?

When a solution of an acid is diluted, the concentration of hydronium ions (H₃O+) decreases. The dilution process involves adding more solvent (usually water) to the acid solution, which reduces the concentration of all solute particles, including hydronium ions.

The relationship between concentration, volume, and moles of solute in a solution is given by the equation:

C₁V₁ = C₂V₂

where:

» C₁ is the initial concentration of the solution,
» V₁ is the initial volume of the solution,
» C₂ is the final concentration of the solution after dilution, and
» V₂ is the final volume of the solution after dilution.

When diluting an acid, V₂ is greater than V₁ because you are adding more solvent. Since C₁ V₁ = C₂ V₂, if V₂ increases, C₂ must decrease.

So, as you dilute the acid, the concentration of hydronium ions (H₃O+) decreases in accordance with the dilution formula. It’s important to note that the total number of moles of hydronium ions remains constant; only the concentration changes due to the addition of more solvent.