11.2 NOTES Fossil Fuels and Energy

Humans have used petroleum in small amounts for 5000 years Only recently (1859) has consumption increased

Chem Quandry 1: Energy Tracing of a Paperclip What general events must have occurred to produce the paper clip and delivery it to CHS? Mine ore Process ore Form steel/aluminum Draw into wire Cut wire Bend clips Packaging Transport to retailer Transport to school From where did the energy for each even come? Petroleum, coal, wood (packaging), nitroglycerin (mining, TNT) In your view, is the total cost of a box of paper clips related more to the materials used (the metals in the alloy) or the energy required? The total cost is more related to the energy rather than the materials.

B.1 Energy and Fossil Fuels Come from biomolecules of prehistoric plants and animals   Biomolecules  molecule that comes from living things The energy in fossil fuels comes from the energy plants gain during photosynthesis

There are several different types, including petroleum, coal, and natural gas Sometimes called buried sunshine Plants originally got energy from the sun through the photosynthesis and the plants undergo changes underground   How are these fossil fuels formed? Extreme pressure and heat; microbes also help the process

Potential energy Kinetic energy Stored energy, energy of position (gravitational) or condition   Kinetic energy Energy of motion

Forms of Kinetic Energy Forms of Potential Energy Motion Gravitational Heat (Thermal) Chemical Sound Stored Mechnical (springs, rubber bands) Radiation Nuclear Electrical  

Energy stored in chemical bonds, potential   Energy is released when bonds are formed. Example Reaction: CH4 + O2  CO2 + 2H2O + ENERGY!

Thermal energy Heat energy   Endothermic changes Need energy in order to occur – absorbs energy All Bond breaking steps are endothermic Energy is a reactant Energy + AB  A + B Exothermic reactions Give off the energy until all energy is used up – releases energy Product in the reaction Occurs during the formation of bonds X + Y  XY + Energy

If more energy is given off than absorbed, it is an exothermic reaction If more energy is absorbed than given off, it is an endothermic reaction Potential energy can be converted to kinetic energy The energy in a reaction can be reversible 2H2 + O2  2H2O + Energy Exothermic Energy + 2H2O  2H2 + O2 Endothermic

B.2 Energy Conversion Energy goes through several conversions in order to be used. You can’t use coal directly to turn on a light. Law of conservation of energy Energy cannot be created or destroyed in a chemical, physical or mechanic process “lost” energy is converted to thermal energy  

B.4 Energy Efficiency We need to reduce the number of energy conversions and increase the efficiency of the device Each time energy is converted from one form to another, energy is lost in the form of heat Many devices are less than 50% efficient They can produce harmful byproducts Energy is given off as heat that can’t do useful work

COMPLETE ACTIVITY! We will go over it in a few…..