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- 1. 25.5 Hydrocarbons from Earth
- 2. Natural Gas Fossil fuels provide much of the world’s energy Natural gas and petroleum contain mostly the aliphatic (or straight-chain) hydrocarbons – formed from marine life buried in sediment of the oceans Natural gas is an important source of alkanes of low molecular mass
- 3. Natural Gas Natural gas is typically: 80% methane, 10% ethane, 4% propane, and 2% butane with the remainder being nitrogen and higher molar mass hydrocarbons also contains a small amount of He, and is one of it’s major sources
- 4. Natural Gas Natural gas is prized for combustion, because with adequate oxygen, it burns with a hot, clean blue flame: CH 4 + 2O 2 CO 2 + 2H 2 O + heat Incomplete burning has a yellow flame, due to glowing carbon parts, as well as making carbon monoxide
- 5. Petroleum The compounds found in petroleum (or crude oil) are more complex than those in natural gas Usually straight-chain and branched-chain alkanes, with some aromatic compounds also Crude oil must be refined (separated) before being used
- 6. Petroleum It is separated by distillation into fractions, according to boiling pt. Fractions containing higher molar mass can be “ cracked ” into more useful shorter chain components, such as gasoline and kerosene involves catalyst and heat starts materials for plastics and paints
- 7. Coal From huge fern trees and mosses decaying millions of years ago under great pressure of rocks / soil. Stages in coal formation: 1. Peat - soft, fibrous material much like decayed garden refuse; high water content. After drying will make a low-cost, smoky fuel
- 8. Coal 2. Lignite - peat left in the ground longer, loses it’s fibrous texture, and is also called brown coal harder than peat; higher C content (50%); still has high water content 3. Bituminous , or soft coal- formed after more time; lower water content, higher C content (70-80%)
- 9. Coal 4. Anthracite , or hard coal carbon content exceeding 80%, making it an excellent fuel source Coal may be found close to the surface (strip-mined), or deep within the earth Pollutants from coal are common; soot and sulfur problems
- 10. BIG BRUTUS Dragline used to remove the overburden of a strip mining coal field near West Mineral, Kansas Note the man standing beside it
- 11. Coal Coal may be distilled for many products coal gas, coal tar, coke, and ammonia further distilled into benzene, toluene, naphthalene, phenol- the aromatics Coke is almost pure carbon; produces intense heat and little or no smoke, thus used in industrial processes