# Question #4a869

Nov 2, 2015

${H}_{2} O$ ($l$) + $C {O}_{2}$ ($g$) = ${H}_{2} C {O}_{3}$ ($a q$)
${H}_{2} O$ ($l$) + ${H}_{2} C {O}_{3}$ ($a q$) = $H C {O}_{3}^{-}$ ($a q$) + ${H}_{3} {O}^{+}$ ($a q$)

#### Explanation:

Natural rainwater is already slightly acidic (pH 5.6) due to the presence of $C {O}_{2}$ in our system (the air that we, humans and animals alike, breathe out and also, a product of organic decomposition).

But the slightly acidic condition is further aggravated by the presence of industrial pollutants like sulfur dioxide ($S {O}_{2}$) and nitrogen oxides ($N {O}_{x}$), to say the least.

So not only does the above chemical formula to describe acid rain, but you can also use these formulas:

${H}_{2} O$ ($l$) + $S {O}_{3}$ ($g$) = ${H}_{2} S {O}_{4}$ ($a q$)

${H}_{2} O$ ($l$) + $2 N {O}_{2}$ ($g$) = $H N {O}_{3}$ ($a q$) + $H N {O}_{2}$ ($g$)

Combination of all these acids in our atmosphere can bring about acid rain.