# How do you calculate the pH of acid rain?

Dec 20, 2016

Acid rain will have a pH ≈4, see below

#### Explanation:

pH is an expression of the hydrogen ion concentration within a solution.

Mathematically, the pH will equal $- {\log}_{10} \left[{H}^{+}\right]$, or the negative logarithm of the molar concentration of hydrogen ion about the solution.

We would need to make this calculation for any relevant solution in question to determine its pH value.

Rainwater itself is known to be slightly acidic, and its pH will vary about the sampled solution. A normal pH value for rain water would be somewhere around $5 - 5.5$.

For acid rain, we can expect the pH value to be lower, around $4$.