# Acid rain is a serious environmental problem. A sample of rainwater collected in the Adiron- dack Mountains had an H+ concentration of .001 mol/L. What is the pH of this sample?

Sep 1, 2016

$p H = - {\log}_{10} \left[{H}_{3} {O}^{+}\right]$, or $p H = - {\log}_{10} \left[{H}^{+}\right]$.
In your example $p H = 3$ clearly.
If $\left[{H}^{+}\right] = {10}^{-} 3 m o l \cdot {L}^{-} 1$, $p H = 3$.
I suspect that this measurement is incorrect, because that is a seriously acid sample of rain water. I wouldn't want to be out in the rain that day! If this is a real measurement, the collected water has likely leached acid salts from the minerals where it pooled. The $p H$ of normal rainwater is approx. $6$.