Online Tool Store
pH Scale Explainer
pH Scale Explainer shows the concentration behind the number, which is where the tenfold-per-unit jump stops being abstract.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Education
pH Scale Explainer
Frontend preview — no upload or external service.
At this pH
pH 4.5 = moderately acidic. H⁺ concentration: 3.16 × 10⁻⁵. Common examples: orange juice, tomato juice.
How the pH Scale Explainer works
- Set a pH value and read the hydrogen ion concentration behind it.
- Compare two values. The scale is logarithmic, so the gap between pH 3 and pH 5 is a hundredfold, not a doubling.
- Note the temperature. Neutral pH is 7 at 25 degrees and shifts with temperature, which surprises people using pH meters in the field.
The method
pH is the negative logarithm of hydrogen ion concentration, which is why each unit is a factor of ten.
pH = -log10[H+]
A change from pH 6 to pH 4 is a hundredfold increase in acidity — the reason a small pH shift in a river or an aquarium is a large chemical change.
FAQ
Why is one pH unit a tenfold change?
Because pH is a base-10 logarithm of concentration. Each whole unit down multiplies hydrogen ion concentration by ten, which is why pH 4 is a hundred times more acidic than pH 6.
Is pH 7 always neutral?
At 25 degrees Celsius, yes. Neutrality is where hydrogen and hydroxide concentrations are equal, and that point shifts with temperature — pure water at 50 degrees is neutral at around pH 6.6.
Can pH go below 0 or above 14?
Yes. The 0 to 14 range covers dilute aqueous solutions, and concentrated strong acids and bases genuinely fall outside it. The scale has no hard limits, only practical ones.
How we compare
| Feature | Online Tool Store | Pen and paper | A classroom platform |
|---|---|---|---|
| Shows ion concentration | ✓ | ✗ | Sometimes |
| Explains the logarithm | ✓ | ✗ | ✗ |
| No sign-up | ✓ | ✓ | ✗ |
| Nothing uploaded | ✓ | ✓ | ✗ |
pH Scale Explainer shows the concentration behind the number, which is where the tenfold-per-unit jump stops being abstract.