The pH of a solution is calculated by taking the negative logarithm of the hydrogen ion concentration.
Explained without symbols:
- First, determine the concentration of hydrogen ions (H⁺) in the solution.
- Then, take the logarithm (base 10) of that value.
- Finally, change the sign to positive (because of the “negative log” rule).
Meaning:
- A high concentration of hydrogen ions gives a low pH, meaning the solution is acidic.
- A low concentration of hydrogen ions gives a high pH, meaning the solution is basic.
- A pH of 7 indicates a neutral solution (like pure water at room temperature).
In short: The pH formula converts the hydrogen ion concentration into a simple scale (0–14) that tells us whether a solution is acidic, neutral, or basic.