1. Acid Deposition

2. pH Scale 7 is neutral As numbers decrease, acidity increases As numbers increase, alkalinity increases

3. pH Scale Q - How much more acidic is a pH of 3 than a pH of 7? A – 10,000 times pH is a logarithmic scale

4. Rain From a natural and unpolluted atmosphere has a pH of close to 6.0 Results form reaction of water vapor and CO 2 in the atmosphere forming a weak carbonic acid (H 2 CO 3 ): CO 2 (g) + H 2 O(l) H 2 CO 3 (aq) Since carbonic acid is a weak acid it partially dissociates: CO 2 (g) + H 2 O(l) H + (aq) + HCO 3 - (aq)

5. Acid Rain Has a pH below 5.6 Reaction of water vapor with sulfur dioxide (SO x ) and nitrogen oxides (NO x )

6. Acid Rain form Sulfur compounds (SO x ) Sulfur dioxide reacts with water to form sulfurous acid (H 2 SO 3 ): SO 2 (g) + H 2 O(l) H 2 SO 3 (aq) Sulfur dioxide (SO 2 ) can be oxidized gradually to sulfur trioxide (SO 3 ): 2SO 2 (g) + O 2 (g) 2SO 3 (g) Sulfur trioxide (SO3) reacts with water to form sulfuric acid (H2SO4): SO 3 (g) + H 2 O(l) H 2 SO 4 (aq)

7. Acid Rain from Nitrogen compounds (NO x ) Oxides of nitrogen, particularly nitrogen dioxide (NO 2 ) react with water to form nitrous acid (HNO 2 ) and nitric acid (HNO 3 ): 2NO 2 (g) + H 2 O(l) HNO 2 (aq) + HNO 3 (aq)

8. Effects of Acid Rain Damages buildings and marble statues by reacting with calcium carbonate to from soluble calcium hydrogen carbonate (calcium bicarbonate, Ca(HCO 3 ) 2 ): CaCO 3 + acid rain Ca(HCO 3 ) 2

9. Effects of Acid Rain

10. Leaches aluminum and calcium form the soil into the ground water, lakes and rivers; poisoning fish and plant roots Aluminum reacts negatively with the gills of the fish irritating them causing a build up of mucous resulting in suffocation

11. Effects of Acid Rain Disrupts the process of photosynthesis Damages plant life Slows the production of chlorophyll Sulfuric acid kills plants “Crown dieback” Leaves at the top (crown) of trees die Leaving a sparse thin crown that progressively increases and moves its way down the tree

12. Crown Dieback

13. Assignment 3.5.1 and 3.5.2 – Chemistry of acid Precipitation and Possible Effects