Question

The acids present in acid rain are___________.

• A. $HN{O}_3$
• B. $H_{2}C{O}_3$
• C. $H_{2}S{O}_4$
• D. Peroxyacetyl Nitrate

Answer 1

Answer: (A), (B), (C)

$H_{2}S{O}_4$

Rainwater has a pH of 5.6 due to the presence of $H^{+}$ ions formed by the reaction of rainwater with carbon dioxide present in the atomsphere.

$H_{2}O\left(l\right)+C{O}_2\left(g\right)\rightleftharpoons H_{2}C{O}_3\left(aq\right)$

$H_{2}C{O}_{3\left(aq\right)}\rightleftharpoons H^{+}\left(aq\right)+HC{O}_3^{-}\left(aq\right)$

When the pH of the rainwater drops below 5.6, it is called acid rain. $S{O}_2$ and $N{O}_2$ after oxidaion and reaction with water are major contributors to acid rain.

$2S{O}_2\left(g\right)+O_2\left(g\right)+2H_{2}O\left(l\right)\to 2H_{2}S{O}_4\left(aq\right)$

$4N{O}_2\left(g\right)+O_2\left(g\right)+2H_{2}O\left(l\right)\to 4HN{O}_3\left(aq\right)$

Hence, options (B),(C) and (D) are correct.