A strong acid, such as hydrochloric acid, at a concentration of 1 mol dm−3 (which means one mole per cubic decimeter, a standard measure of concentration), has a pH of 0.
Understanding pH 0
A pH value of 0 indicates an extremely high level of acidity. The pH scale measures the concentration of hydrogen ions (H⁺) in a solution, which dictates its acidity or alkalinity.
- Extremely Acidic: Solutions with a pH of 0 are at the lowest end of the typical pH scale, signifying a very high concentration of hydrogen ions.
- Strong Acids: Acids like hydrochloric acid (HCl) are classified as "strong" because they fully dissociate in water, releasing all their hydrogen ions into the solution, leading to a very low pH.
The pH Scale Explained
The pH scale is a fundamental concept in chemistry, ranging typically from 0 to 14. It is a logarithmic scale, meaning each whole number change in pH represents a tenfold difference in hydrogen ion concentration.
- Acidity: pH values less than 7 indicate acidity. The lower the number, the stronger the acid.
- Neutrality: A pH of 7 is neutral, like pure water at 25°C.
- Alkalinity (Basicity): pH values greater than 7 indicate alkalinity or basicity. The higher the number, the stronger the alkali. For instance, a strong alkali like sodium hydroxide at a concentration of 1 mol dm−3 has a pH of 14.
To illustrate the range and significance of pH values:
| pH Value Range | Characteristic | Examples |
|---|---|---|
| 0 - <7 | Acidic | Battery acid (pH < 1), Lemon juice (pH 2), Vinegar (pH 2.5) |
| 7 | Neutral | Pure Water |
| >7 - 14 | Alkaline (Basic) | Baking soda (pH 8.5), Ammonia (pH 11), Drain cleaner (pH 13-14) |
Key Takeaways
- A pH of 0 signifies a highly concentrated strong acid.
- Hydrochloric acid at a specific concentration (1 mol dm−3) is a common example of a substance with a pH of 0.
- The logarithmic nature of the pH scale means even small changes in pH represent significant changes in acidity or alkalinity.
