pH
Definition
A logarithmic scale (0–14) measuring the acidity or basicity of a solution. pH = -log[H⁺]. pH 7 is neutral; below 7 is acidic; above 7 is basic.
Why is pH Important?
pH is an essential chemistry concept used in laboratories, pharmaceutical development, environmental science, and industrial processes. Understanding this concept is critical for accurate chemical calculations, safe laboratory practices, and optimizing reactions.
Our chemistry calculators provide instant, accurate results for complex conversions and calculations, making lab work more efficient and reducing the risk of errors in critical measurements.
What is pH?
The pH scale measures the acidity or basicity (alkalinity) of a solution on a scale of 0 to 14. It is defined as pH = −log₁₀[H⁺], where [H⁺] is the hydrogen ion concentration in moles per liter. Each whole pH number represents a 10-fold change in acidity.
The pH Scale
| pH | Type | H⁺ Concentration | Example |
|---|---|---|---|
| 0 | Strongly acidic | 1 M | Battery acid |
| 1 | Very acidic | 0.1 M | Hydrochloric acid |
| 2 | Acidic | 0.01 M | Lemon juice, vinegar |
| 3 | Acidic | 0.001 M | Orange juice, soda |
| 4 | Mildly acidic | 10⁻⁴ M | Tomato juice, acid rain |
| 5 | Slightly acidic | 10⁻⁵ M | Coffee, banana |
| 6 | Slightly acidic | 10⁻⁶ M | Milk, saliva |
| 7 | Neutral | 10⁻⁷ M | Pure water |
| 8 | Slightly basic | 10⁻⁸ M | Seawater, eggs |
| 9 | Basic | 10⁻⁹ M | Baking soda |
| 10 | Basic | 10⁻¹⁰ M | Milk of magnesia |
| 11 | Very basic | 10⁻¹¹ M | Ammonia |
| 12 | Very basic | 10⁻¹² M | Soapy water |
| 13 | Strongly basic | 10⁻¹³ M | Bleach, oven cleaner |
| 14 | Very strongly basic | 10⁻¹⁴ M | Drain cleaner (NaOH) |