What is the neutralizing effect of pure water on acids and bases?

Pure water has a neutralizing effect on acids and bases primarily because it serves as a solvent that dilutes both substances. When an acid or base is mixed with pure water, the concentration of hydrogen ions (H⁺) from the acid or hydroxide ions (OH⁻) from the base decreases due to the increased volume of the solution. This dilution leads to a reduction in the overall acidity or basicity of the solution, thereby weakening the effects of the acid or base.

For example, when hydrochloric acid (HCl), a strong acid, is added to water, the H⁺ ions disperse throughout the larger volume of water, thereby lowering the concentration and reducing its corrosive properties. Similarly, adding water to sodium hydroxide (NaOH), a strong base, likewise dilutes its hydroxide ions, which decreases its strong basic properties.

Therefore, the statement that water weakens acids and bases accurately captures this neutralizing action, as it demonstrates how pure water modulates the strengths of these substances through dilution.