Environmental Chemistry Question 7
Question 7 - 31 January - Shift 2
The normal rain water is slightly acidic and its $pH$ value is 5.6 because of which one of the following ?
(1) $CO_2+H_2 O \to H_2 CO_3$
(2) $4 NO_2+O_2+2 H_2 O \to 4 HNO_3$
(3) $2 SO_2+O_2+2 H_2 O \to 2 H_2 SO_4$
(4) $N_2 O_5+H_2 O \to 2 HNO_3$
Show Answer
Answer: (1)
Solution:
Formula: Acid Rain
We are aware that normally rain water has a $pH$ of 5.6 due to the presence of $H^{+}$ions formed by the reactions of rain water with carbon dioxide present in the atmosphere.
$ \begin{aligned} & H_2 O(l)+CO_2(g) \leftrightharpoons H_2 CO_3(aq) \\ & H_2 CO_3(aq) \leftrightharpoons H^{+}(aq)+HCO_3^{-}(aq) \end{aligned} $
