The pH of a solution with a hydrogen ion concentration of 0.01 mole per liter is 2.
Understanding pH and Hydrogen Ion Concentration
The pH scale is a fundamental metric used to determine the acidity or alkalinity of an aqueous solution. It quantifies the concentration of hydrogen ions (H⁺) present in the solution. A higher concentration of hydrogen ions signifies a more acidic solution, resulting in a lower pH value. Conversely, a lower concentration of hydrogen ions indicates a more alkaline (basic) solution, leading to a higher pH.
The relationship between pH and the hydrogen ion concentration is logarithmic and is expressed by the formula:
pH = -log₁₀[H⁺]
Where [H⁺] represents the molar concentration of hydrogen ions in moles per liter.
Calculating pH for a 0.01 M H⁺ Concentration
To determine the pH for a solution with a hydrogen ion concentration of 0.01 mole per liter (0.01 M), we can apply the pH formula:
- Express the concentration in scientific notation: 0.01 M is equivalent to 1 x 10⁻² M.
- Apply the pH formula:
- pH = -log₁₀(0.01)
- pH = -log₁₀(10⁻²)
- Since log₁₀(10ˣ) = x, then log₁₀(10⁻²) = -2.
- pH = -(-2)
- pH = 2
This calculation directly shows that a hydrogen ion concentration of 0.01 M results in a pH of 2.
Relationship Between Hydrogen Ion Concentration and pH
The table below illustrates the inverse logarithmic relationship between hydrogen ion concentration and pH values:
| Hydrogen Ion Concentration (mole/liter) | pH |
|---|---|
| 0.1 (1 x 10⁻¹ M) | 1 |
| 0.01 (1 x 10⁻² M) | 2 |
| 0.001 (1 x 10⁻³ M) | 3 |
| 0.0001 (1 x 10⁻⁴ M) | 4 |
| 0.00001 (1 x 10⁻⁵ M) | 5 |
As observed, each tenfold decrease in hydrogen ion concentration (e.g., from 0.1 M to 0.01 M) corresponds to an increase of one unit on the pH scale. This characteristic makes the pH scale highly effective for representing a vast range of acidity and alkalinity with easily manageable numbers.
Practical Implications of pH 2
A solution with a pH of 2 is considered strongly acidic. For context:
- Acids have a pH less than 7.
- Bases (alkaline solutions) have a pH greater than 7.
- Neutral solutions have a pH of exactly 7 (e.g., pure water at 25°C).
Examples of everyday substances with a pH around 2 include lemon juice and gastric acid (stomach acid). Solutions at this pH are typically corrosive and require careful handling.
