A pH of 7 is considered neutral because in pure water, the concentration of hydrogen ions (H+) is about equal to a pH of 7.
Understanding pH and Neutrality
The pH scale measures how acidic or basic (alkaline) a substance is. It ranges from 0 to 14:
- pH < 7: Acidic (more H+ ions)
- pH = 7: Neutral (balanced H+ and OH- ions)
- pH > 7: Basic or alkaline (more OH- ions)
How 7 Becomes Neutral
In pure water, there's a natural process where some water molecules split into hydrogen ions (H+) and hydroxide ions (OH-).
| Ion | Charge |
|---|---|
| Hydrogen (H+) | +1 |
| Hydroxide (OH-) | -1 |
According to the reference, "The amount of H+ that is made in pure water is about equal to a pH of 7". Because the amount of H+ ions and OH- ions are equal, the charges are balanced, resulting in a neutral solution. Therefore, a pH of 7 is the point where acidity and basicity are balanced.
Key Takeaway
The neutrality at a pH of 7 comes from the equilibrium of H+ and OH- ions in pure water, making it the standard reference point for a neutral solution.
