What is the pH of a neutral solution at 25°C?

In a neutral solution at 25°C, the concentration of hydrogen ions (H⁺) and hydroxide ions (OH⁻) is equal, resulting in a pH of 7. This value is a standard reference point in chemistry, indicating that the solution is neither acidic nor basic.

The pH scale ranges from 0 to 14, where values less than 7 indicate acidity (higher concentration of H⁺ ions) and values greater than 7 indicate alkalinity (higher concentration of OH⁻ ions). At 25°C, water itself is neutral, and due to the autoionization of water, where water molecules dissociate into H⁺ and OH⁻, both ions have concentrations of 1 × 10⁻⁷ M, leading to a pH calculation of -log(1 × 10⁻⁷), which equals 7.

Thus, a neutral solution's pH of 7 is a fundamental concept in understanding acid-base chemistry, establishing a baseline for comparing the acidity or basicity of other solutions.