The average concentration of `SO_(2)` in the atmosphere over a city on a certain day is `10 ppm`, when the average temperature is `298 K`. Given that the solubility of `SO_(2)` in water at `298k`. Given that the solubility of `SO_(2)` in water at `298K` is `1.3653mol L^(-1)` and `pK_(a)` of `H_(2)SO_(3)` is `1.92`. Estimate the `pH` of rain on that day.

Explanation

Partial pressure of `SO_(2)`in air = `10^(-5)`atm
`[SO_(2)]_(aq) = 1.3653 xx 10^(-5)molL^(-1)`
`:' pK_(a) = 1.92` and concentration of `H_(2)SO_(3)` is very low, it is almost completely iodised as:
`H_(2)SO_(3) rarr H^(+) + HSO_(3)^(-)`
`[H^(+)] = 1.3653 xx 10^(-5)M`
`pH = -log(1.365 xx 10^(-5)) = 4.86`