Neutral

Definition

A neutral solution has a pH of 7, meaning it is neither acidic nor basic. It contains equal concentrations of hydrogen ions (H\(^+\)) and hydroxide ions (OH\(^-\)).

5 Must Know Facts For Your Next Test

1. Pure water at 25°C is neutral with a pH of exactly 7.
2. In a neutral solution, the concentration of H\(^+\) ions equals the concentration of OH\(^-\) ions, both being $1 \times 10^{-7}$ M.
3. Neutrality can be disturbed by adding acids or bases which shift the pH away from 7.
4. The concept of neutrality is central to understanding acid-base equilibria and buffer solutions.
5. At temperatures other than 25°C, the value for neutral pH can shift slightly due to changes in the ion product of water (K\(_w\)).

Review Questions

• What is the pH value of a neutral solution at standard temperature?
• How do the concentrations of H\(^+\) and OH\(^-\) ions compare in a neutral solution?
• What happens to the neutrality of a solution if an acid or base is added?

Related terms

pH:

A measure of the hydrogen ion concentration in a solution; calculated as $ - \log[H^+]$.

pOH:

A measure of the hydroxide ion concentration in a solution; calculated as $ - \log[OH^-]$.

Buffer Solution:

A system that resists changes in pH when small amounts of acids or bases are added.