+ Chapter 3 Science, Systems, Matter and Energy. + What is Energy? The capacity to do work and transfer heat Kinetic Energy Matter has because of its.

+

Chapter 3Science, Systems, Matter and Energy

+What is Energy?The capacity to do work and transfer heat

Kinetic Energy

Matter has because of its mass and speed

Potential Energy

Stored and potentially available for use

Potential energy can be changed to kinetic energy!

+Electromagnetic RadiationEnergy radiated in the form of a wave as a result of changing electric and magnetic fields

+What is Heat and How is it Transferred?The total kinetic energy of all moving atoms, ions, molecules in a given substance

What is Energy Quality?A measure of an energy source’s ability to do useful

work

Industrial processesProducing electricity to run lights, motors

Mechanical motionIndustrial processesProducing electricity

Moderate-temp heat for industrial processes, cooking, steam, electricity

Low-temp heat for space heating

+Physical vs. Chemical Change

No change in chemical composition

Composition of the elements or compounds are altered

Physical Change Chemical Change

+Law of Conservation of Matter

We may change various elements and compounds from one physical or chemical form to another, but we cannot create or destroy any of the atoms involved

There is really no AWAY in “to throw away”

+3 Factors Determining

Pollutant’s Harmful Effects

1. Chemical Nature

2. Concentration: 1 part pollutant to how ever many parts of gas, liquid or mixture pollutant is found in

Parts per million (ppm) Parts per billion (ppb) Parts per trillion (ppt)

+3 Factors Determining

Pollutant’s Harmful Effects

3. Persistence: how long it stays in the air, water, soil or body

Degradable (non-persistent): broken down completely or reduced to acceptable levels by natural physical, chemical, and biological processes

Human sewage in a river, degrades quickly by bacteria Slowly degradable (persistent): take decades or

longer to degrade Insecticide and most plastics

Nondegradable: cannot be broken down by natural processes

Toxic elements such as lead, mercury, arsenic

+Nuclear Change

Natural Radioactive Decay Unstable isotope emits a fast-moving particle, high-energy radiation, or

both Decay continues into various isotopes until original is changed into a stable

isotope

Gamma rays are most common form of ionizing radiation emitted

Alpha particles: fast moving,

positively charged, 2 protons

+ 2 neutronsBeta particles: high-speed electrons

+Nuclear Change Nuclear Fission

Nuclei of certain isotopes with large mass numbers (Uranium-235) are split apart into lighter nuclei when struck by neutrons

Critical Mass: enough fissionable material is present for multiple fissions to occur forming a chain reaction

+Nuclear Change

Nuclear Fusion Two isotopes of light

elements are forced together at extremely high temperatures until they fuse

Form a heavier nucleus, releasing energy Requires temp of at least

100 million °C More difficult to initiate, but

releases much more energy per unit than fission

+Radiation Exposure

What are some sources of radiation you come into contact with frequently?

http://abcnews.go.com/Health/radiation-exposure-things/story?id=13131122

What are the effects of ionizing radiation? Genetic damage Somatic damage

+First Law of Thermodynamics

Also known as the Law of Conservation of Energy

Energy cannot be created or destroyed, only converted from one form to another

When one form of energy is converted to another form (physical or chemical change) the energy input = output

You cannot get something from nothing

+

+Second Law of Thermodynamics

Burning gas in a car or using up a battery, something has been lost. If it isn’t energy what is it? Energy Quality: amount of energy available to do useful

work

When energy is changed from one form to another there is ALWAYS a decrease in energy quality Lower quality More dispersed Less useful

You cannot break even

+

What do a car, a light bulb and food have in

common?

+Where does the energy go?

Only ~10% high-quality energy available in gasoline’s fuel which is converted to mechanical energy Remaining 90% degraded to low-quality heat, release to

space

Electrical flow through filament changed to 5% useful light Remaining 95% low-quality heat to environment

Solar energy converted to chemical energy (plants) and then into mechanical energy (moving, living) Your body continuously gives of heat

+2nd Law of Thermodynamics Cont.

We can never recycle or reuse high-quality energy to perform useful work

Can heat air or water at low temperature to upgrade to high-quality energy BUT it will take more energy than we can get in return

Energy use estimates in the US 16% for useful work 41% unavoidably wasted 43% unnecessarily wasted