Chapter 15: Energy

CFE, SP26

energy

the ability to do work or transfer heat

joule

SI unit of energy

Potential energy

energy of position or stored energy

Kinetic energy

energy of motion

biosphere

thin film of air, water, and soil where life exist

30%

solar radiation reflected back to space

23%

solar radiation powers the water cycle

<0.02%

used by green plants to power photosynthesis

photosynthesis

produces oxygen and stores energy for all animals on the planet

temperature

increasing temperature increases reaction rates (more collisions)

Concentration of reactants

reaction rates are dependent on reactant concentration. As concentration increases, rate increases. (more collisions)

Presence of catalysts

Catalysts increases the rate of reaction by lowering activation energy (effective collisions)

Exothermic reactions

release heat energy to the surroundings

Endothermic reactions

absorbs heat energy from the surroundings

Freezing water

exothermic

melting ice

endothermic

energy can be neither created nor destroyed

law of conservation of energy

Thermodynamics

energy flows spontaneously from hot objects to cooler objects until temps are equal

Entropy

measure of dispels of energy, all spontaneous process, the entropy of the universe is increasing

Fossil fuels

coal, oil, natural gas, provides more than 90% of the energy consumed in a modern society

Fuels

substance when burned, release significant amounts of energy

combustion

oxidation process that is exothermic

coal

hazardous to obtain and inconvenient to use due to its solid nature

natural gas

cleanest burning fossil fuels

Mathane

natural gas

Liquid hydrocarbons

petroleum

Petroleum

complex mixture of hydrocarbons, combustions with oxygen

Petroleum comes from…

crude oil, separated into fractions for use (by boiling)

Gasoline

lighter fraction from crude oil, mixture of more than 150 different compounds

cracking

breaking big molecules into small molecules

straight-run gasoline

gasoline fraction that comes from a distillation column

Knocking

occurs when the fuel combusts before the spark plug fire

octane rating of gasoline

measure of the fuel’s ability to resist knocking

electricity

most convenient fuel of all

Nuclear Fission

Nuclear Energy

Solar energy

energy from the sun diffuse and concentrated to make it useful

Solar collectors

absorb solar energy and use it to heat water

burning plant material

by-products is one means of harvesting energy from the sun

Hydrogen

burned cleanly as fuel or used in fuel cells

Wind and water

used to turn turbines and produce electricity

Geothermal Energy

water pimped to the interior of Earth, where it is heated and converted to steam

Which process is exothermic?

a lake freezing

Consider the statement “Striking a match is an endothermic process because the air near the burning match is absorbing heat.” Which of the following analyses of this statement is true?

The statement is false, but the reason is true

According to the first law of thermodynamics, energy can be converted from one form to another, but it can neither be created nor destroyed.

True

The fact that a heat pump requires energy to move heat from a colder object (the outside of a house) to a hotter object (the inside of the house) is a real life observation of which thermodynamic law?

2nd law

Which process is an example of entropy decreasing?

Steam condenses to liquid water