Acid Deposition

Question 1

What is the normal pH range of water?

Answer 1

pH 5.6 to pH 7

Question 2

Below what threshold is rainwater considered acidic?

Answer 2

pH 5.6

Question 3

Define the term ‘acid deposition’

Answer 3

Any process in which acidic substances leave the atmosphere

Question 4

Differentiate between dry and wet deposition

Answer 4

Dry: e.g. acidic gases, particlesWet: e.g. acid rain, snow, fog

Question 5

Define the process by which hydroxyl radicals are produced in the atmosphere

Answer 5

O3 –> O2 + O•O• + H2O –> 2HO•

Question 6

Define how NO is oxidized to NO2

Answer 6

2NO + O2 –> 2NO2

Question 7

Define the processes by which HNO3 and HNO2 are produced via the HO• radical

Answer 7

HO• + NO2 –> HNO3HO• + NO –> HNO2

Question 8

Define the process by which SO3 and H2SO4 are produced in the atmosphere

Answer 8

HO• + SO2 –> HOSO2•HOSO2• + O2 –> HO2• + SO3SO3 + H2O –> H2SO4

Question 9

Define the process by which H2SO3 is produced in the atmosphere

Answer 9

S + O2 –> SO2 SO2 + H2O –> H2SO3

Question 10

Define two alternative pathways for the production of HNO3 in the atmosphere that do not involve the HO• radical

Answer 10

4NO2 + O2 + H2O –> 4HNO32NO2 + H2O –> HNO2 + HNO3

Question 11

What effect does acid deposition have on vegetation?

Answer 11

H+ ions displace metals in the soil (Mg+, Ca+, K+).Mg+ is needed for production of chlorophyll, which plants withdraw from the soil

Question 12

What effect does acid deposition have on Lakes and Rivers?

Answer 12

Below pH 5.2 fish and invertebrates cannot survive. H+ removes Al from soil, converting it to (Al)3+(Al)3+ can damage fish gills

Question 13

Define the reaction given for the effect if acid deposition on limestone structures (natural or anthropogenic)

Answer 13

CaCO3 + H2SO4 –> CaSO4 + H2O +CO2

Question 14

Define the process of liming in terms of the reactions used to remove H2SO4 from water sources

Answer 14

CaO + H2SO4 –> CaSO4 + H2OCa(OH)2 + H2SO4 –> CaSO4 + 2H2O