topic 8-Fuels and earth science

• different fractions of crude oil

  1. gases
  2. petrol
  3. kerosene
  4. diesel oil
  5. fuel oil
  6. bitumen
• the longer hydrocarbons have a higher boiling point
• A homologous series is a family of molecules which have the same general formula and share similar chemical properties
• intermolecular forces of attraction break alot easier in small molecules because the forces are much weaker between small molecules
• shorter hydrocarbons are easy to ignite because they have lower boiling points and tend to be gases at room temperature
• longer hydrocarbons are usually liquids at room temperature and have higher boiling points so they are hard to ignite
• viscosity measures how easily a substance flows
• fractions containing longer hydrocarbons have a higher viscosity
• shorter hydrocarbons have a low viscosity and are very runny
• complete combustion

  hydrogen + oxygen --> carbon dioxide + water
• incomplete combustion occurs when a hydrocarbon burns in a limited supply of oxygen
• complete combustion reactions only produce carbon dioxide and water
• carbon monoxide can combine with red blood cells and stop your blood from doing its proper job of carrying oxygen around the body.
• 1. during incomplete combustion, tiny particles of carbon can be released into the atmosphere. When they fall back to the ground, they deposit themselves as soot
• soot makes buildings look dirty, reduces air quality, and can worsen respiratory problems
• Cracking turns long saturated (alkane) molecules into smaller unsaturated (alkene) and alkane molecules
• Vaporised hydrocarbons are passed over a powdered catalyst at 400-700 degrees and 70 atm
• In cracking, the long chain molecules split apart
• Phase 1 volcanoes have out gasses

  1. The early atmosphere was mostly carbon dioxide and almost no oxygen
  2. volcanoes also gave out nitrogen, water vapor, methane, and ammonia
• Phase 2: oceans, algae, and green plants absorbed carbon dioxide

  -water vapor from volcanoes condensed, forming the oceans because of the decrease in earths temperature

  -lots of carbon dioxide dissolved in the ocean, formed sediment on the seabed, or was taken in by green plants and algae for photosynthesis
• Phase 3: green plants and algae produced oxygen

  • as well as taking in carbon dioxide from the atmosphere, green plants and algae gave out oxygen
  • oxygen levels building up in the atmosphere supported more complex life
• You can test for oxygen by checking if the gas will relight a glowing splint
• As the population increases, the concentration of carbon dioxide in the atmosphere increases because more people respire
• The greenhouse effect helps keep the earth warm

  1. the sun gives out electromagnetic radiation
  2. some electromagnetic radiation passes through the atmosphere
  3. the shorter electromagnetic Radiation is absorbed by the earth and warms the planet
• Greenhouse gasses are the gasses in the atmosphere that can absorb and reflect heat radiation
• An enhanced greenhouse effect is where more heat radiation from the earth is absorbed and less is remitted into space
• Historical data is less accurate because it was taken over fewer locations and the methods used were inaccurate