How our use of energy affects our environment

1. How our use of energy affects our environment

2. Most electricity in the USA comes from… • Burning biomass • Burning petroleum • Burning coal • Nuclear • None of these

3. Coal supplies more than half of our electrical energy in the USA. What is a big consequence of burning coal? • It emits sulfur dioxide into the air. • It emits pure oxygen into the air. • It emits ozone destroying compounds. • It emits carbon tetrafluoride into the air. • None of these happen.

4. As you can see, electricity production is the biggest source of anthropogenic Sulfur Dioxide

5. Bituminous Coal typically is 2.5% Sulfur (by mass) This means that if there are no sulfur reduction techniques used… • A 1.7 megawatt electricity generating plant burning 600 tons of bituminous coal per hour, will put about 1100 tons of sulfuric acid in the environment each day. • Petroleum is typically refined with techniques that remove sulfur—thus car emissions do not significantly contribute .

6. So does that mean car emissions don’t significantly affect the environment in a negative way? • Yes—auto emission standards have stopped all forms of pollution—except carbon dioxide. • No—cars still emit Nitrogen Oxides • No—cars still emit Water Vapor

7. Both Nitrogen Oxides & Sulfur Dioxide are things that humans add to air that affects the acidity of rain.

8. Are there any natural sources of sulfur dioxide? • No • Yes—trees • Yes—volcanoes • Yes—earthquakes • Yes—all of 2-4

9. So, what do you know about acid chemistry?

10. What is an acid? • Any substance that burns you if you touch it. • A substance that is highly flammable. • A substance that has a surplus of electrons. • A substance that has a surplus of hydrogen ions.

11. Acids are substances with a surplus of hydrogen ions. • Ions are atoms with an imbalance in their electrical charge • They either have more protons than electrons (positively charged) OR They have more electrons than protons (negatively charged)

12. Ions form naturally all of the time in water… This shows the process of dissociation. But in pure water, the positive and negative ions are in balance overall.

13. Adding a solute to the water can change the balance between H3O+ and OH- ions. • EX. HCL + H2O  H3O+ + Cl- Thus, adding HCL to water changes the ion balance so that there are more Hydronium (+) ions than Hydroxide (-) ions. Thus HCL is an acid.

14. So, why do acids (or bases) tend to react with other substances? Ions have a charge--thus they will be attracted to certain substances in order to balance the charge difference.

15. What is pH? 1) Percent Hydrogen scale 2) Partial Halogen scale 3) Power of the Hydrogen ion scale 4) Pascal’s Histogram scale

16. How does the pH scale indicate acidity? 1) Numbers near 0 are most acidic 2) Numbers near 7 are most acidic 3) Numbers near 14 are most acidic 4) Numbers near 100 are most acidc

17. pH Power of the Hydrogen ion Scale runs from 0 to 14 Seven is neutral < 7 is an acid > 7 is a base

18. In absence of human influence, rainwater would have a pH of… 1) 0 2) 3.5 3) 5.5 4) 7 5) 9.5 6) 14

20. Why is rain naturally acidic? Carbon dioxide in the air combines with water to form H2CO3 (Carbonic Acid) This brings the pH of rainwater down to about 5.5 Rain water is typically less than this due to pollutants of Sulfur Dioxide & Nitrogen Oxides which also make rainwater acidic.

21. What’s the big deal about acid rain? • It inhibits plant growth • It degrades the quality of soils • This is especially bad for growth of crops

22. It also wears down rocks & stone buildings

23. What happened to Cleopatra’s Needle? Statue was stored in a location where it was not exposed to the elements for thousands of years. Then it was brought to New York City & displayed in Central Park. The Hieroglyphics rapidly weathered away due to exposure to rain & the atmospheric pollutants that would make the rain more acidic.