To find the pH of a solution, you need to determine the concentration of hydronium ions (H₃O⁺) in the solution. The pH is then calculated using the following formula:
pH = -log[H₃O⁺]
Where:
- pH is the measure of acidity or alkalinity of a solution.
- log is the base-10 logarithm.
- [H₃O⁺] is the molar concentration of hydronium ions in the solution.
Here's a breakdown of the process:
- Identify the hydrogen ion concentration ([H₃O⁺]). This can be provided in the problem or can be determined by experiment.
- Calculate the negative base-10 logarithm of the hydrogen ion concentration. You can use a scientific calculator to find the log function.
Examples:
- If the [H₃O⁺] is 1 x 10⁻⁴ M, then the pH = -log(1 x 10⁻⁴) = 4.
- If the [H₃O⁺] is 0.001 M, then the pH = -log(0.001) = 3.
Understanding pH Values:
- pH < 7 indicates an acidic solution.
- pH = 7 indicates a neutral solution.
- pH > 7 indicates a basic (or alkaline) solution.
Important Notes:
- The pH scale is logarithmic, meaning that a change of one pH unit represents a tenfold change in the hydronium ion concentration.
- The pH of a solution can be affected by temperature and the presence of other substances.
