Enviromental Chemistry
7.0 Acid Rain
7.0 Acid Rain
Rain occurs when vapours condense in clouds & fall to earth. As it begins to fall, it is neutral
$\left( {pH{\text{ }} = {\text{ }}7} \right).$. While it traves through the air, it dissolves floating chemical & washes down the particles that are suspended in air. These substances make the rain slightly acidic $(pH \approx 6).$. This level of acidity is not dangerous.
However when the rain falls through polluted air, it comes across chemicals such as gaseous oxides of sulphur $\left( {S{O_x}} \right)$, oxides of nitrogen $\left( {N{O_x}} \right)$, mist of hydrochloric acids & phosphoric acid etc. These substances dissolve in falling rain making it more acidic than normal with pH ranging between (5.6 ? 3.5).
