Neutral Solution
A solution in which the concentrations of hydrogen and hydroxide ions are exactly equal.
Formula / equation
[H⁺] = [OH⁻] = √Kw
Unit
mol/L
In depth
Neutrality is defined by the equality of the two ion concentrations, not by a pH of 7. Because Kw increases with temperature, the neutral pH falls below 7 in hot water and rises above it in cold, even though the solution remains perfectly neutral.
Examples in the real world
Pure water at 25 °C has pH 7.00, but at 100 °C neutral water has a pH of 6.14.