1. Department of Chemistry CHEM1020 General Chemistry *********************************************** Instructor: Dr. Hong Zhang Foster Hall, Room 221 Tel: 931-6325 Email: hzhang@tntech.edu

2. CHEM1020/General Chemistry _________________________________________ Chapter 12. (L23)-Chemistry of Earth Today’s Outline …The industrial smog …Acid rain and air pollution …Particular matter

3. Chapter 12. (L23)-Chemistry of Earth Chemistry of industrial smog …Coal has up to ~3% of sulfur When coal is burned, sulfur compounds are also released into the air. Consequence of sulfur compounds release into the air: SO 2  SO 3  H 2 SO 4 (acid rain) Definition of acid rain: rain water pH < 5.6 pH 5.6 is the pH value of the atmospheric water droplets saturated with CO 2. Fine droplets of the acid H 2 SO 4 form an aerosol, a suspension of very small particles of a solid or droplets of a liquid in a gas phase. The aerosol is more irritating than SO 2 gas.

4. Chapter 12. (L23)-Chemistry of Earth Chemistry of industrial smog …Carbon particles from coal burning If the coal is not burned completely, then fine particles of carbon become soot, suspending in the air. It can do much to change the air conditions. …Industrial smog: This is characterized by the presence of smoke, fog, sulfur dioxide, and particular matter such as soot and ash. Burning of coal is mainly responsible for the occurrence of industrial smog.

5. Chapter 12. (L23)-Chemistry of Earth Particular matter in the air …Particular matter (PM) are solid and liquid particles of greater than molecular size. The largest particles are often visible in the air as dust and smoke. PM consists mainly of soot and the mineral matter in coal. Small particles are especially harmful, contributing to respiratory and heart diseases EPA defined small PM: PM 10 : particles of < 10 μm in diameter PM 2.5 : particles of < 2.5 μm in diameter

6. Chapter 12. (L23)-Chemistry of Earth Acid rain and acid deposition …Acid precipitation includes acid rain, acid snow, acid fog, any other acid atmospheric deposition Acid rain mainly comes from SO 2 emitted from power plants and smelters, together with other pollutants such as Hg and from nitrogen oxides released from power plants and automobiles.

7. Chapter 12. (L23)-Chemistry of Earth Acid rain and acid deposition …Consequences of acid precipitation, examples Acids can corrode metals (simplified): Fe(s) + H 2 SO 4  FeSO 4 + H 2 (g) Acids can disintegrate marble buildings and statues and other things made of limestone: CaCO 3 + H 2 SO 4  CaSO 4 + H 2 O + CO 2 Acids can acidify freshwaters like lakes and streams and ponds and thus harm the wildlife.

8. Chapter 12. (L22)-Chemistry of Earth Quiz Time TBA