Interactive pH Scale Chart
Explore the pH scale with real-world examples and detailed explanations
The pH Scale (0-14)
Acidic (pH < 7)
High concentration of H⁺ ions
Neutral (pH = 7)
Equal H⁺ and OH⁻ ions
Basic/Alkaline (pH > 7)
High concentration of OH⁻ ions
Understanding pH
pH stands for "potential of Hydrogen" and measures the concentration of hydrogen ions (H⁺) in a solution. The scale is logarithmic, meaning each unit represents a 10-fold change in acidity.
- pH = -log₁₀[H⁺]
- Lower pH = more acidic
- Higher pH = more basic/alkaline
- pH 7 = neutral (pure water at 25°C)
Logarithmic Scale
The pH scale is logarithmic, which means:
- pH 6 is 10× more acidic than pH 7
- pH 5 is 100× more acidic than pH 7
- pH 4 is 1,000× more acidic than pH 7
- Small changes in pH represent large changes in acidity
Real-World Applications
pH is crucial in many areas:
- Agriculture: Soil pH affects plant growth
- Medicine: Blood pH must stay around 7.4
- Food: pH affects taste and preservation
- Environment: Acid rain impacts ecosystems
- Industry: pH control in manufacturing
Download pH Scale Chart
Get a printable version of our pH scale chart for your classroom or lab.
pH Scale FAQ
The pH scale typically ranges from 0 to 14 because it's based on the water dissociation constant (Kw = 1.0 × 10⁻¹⁴ at 25°C). However, solutions can have pH values outside this range in extreme cases.
Yes! Very concentrated strong acids can have negative pH values, and very concentrated strong bases can have pH values greater than 14. For example, 1M HCl has a pH of 0, but 10M HCl would have a pH of -1.
pH measurements can be very accurate with proper equipment:
- pH meters: ±0.01 pH units
- pH indicator strips: ±0.5 pH units
- Universal indicators: ±1 pH unit
Yes, temperature affects pH because it changes the water dissociation constant (Kw). Pure water at 0°C has a pH of about 7.47, while at 100°C it has a pH of about 6.14, even though it's still neutral.