5 MINUTES TO QUIETLY STUDY FOR YOUR QUIZ

BELLRINGER

•Convert 250 ml to Hl (hecta liters) using dimensional analysis

AGENDA

• Bellringer

• Energy & Matter PowerPoint – Chapter 2

CH. 2 – ENERGY & MATTER

I. ENERGY, TEMPERATURE & HEAT

A. ENERGY

• Energy – the capacity to do work or produce heat.

• Work is the capacity to move an object over a distance against a force; For example: it moves cars, bakes a cake, keeps ice frozen, lights houses, etc.

• Two Kinds:• Kinetic – energy of motion (waves, molecules,

objects) • Potential – stored energy or energy of

position in the chemical bonds

A. ENERGY• Forms of energy:

1.Kinetic energy:

• Electrical

• Radiant

• Thermal

• Motion

• Sound

2. Potential energy

• Chemical

• Stored mechanical

• Nuclear

• Gravitational

A. ENERGY

• Law of Conservation of Energy: • Energy is neither created nor destroyed

• When we use energy, it doesn’t disappear

• It can be changed from one form to another:

• 1).A car burns gasoline, converting the chemical energy into mechanical energy 2). Solar cells change radiant energy into electrical energy

A. US ENERGY CONSUMPTION

•Renewable

•Biomass 2.9%

•Hydropower 2.7%

•Geothermal 0.3%

•Wind 0.1%

•Solar & other 0.1%

Nonrenewable

•Petroleum 38.1%

•Natural Gas 22.9%

•Coal 23.2%

•Nuclear (uranium) 8.1%

•Propane 1.7%

B. KINETIC MOLECULAR THEORY

• KMT

• Particles of matter are always in motion.

• The kinetic energy (speed) of these particles (atoms) increases as temperature increases.

C. FOUR STATES OF MATTER• Solids

• very low KE - particles vibrate but can’t move around

• fixed shape

• fixed volume

C. FOUR STATES OF MATTER• Liquids

• low KE - particles can move around but are still close together

• variable shape

• fixed volume

C. FOUR STATES OF MATTER• Gases

• high KE - particles can separate and move throughout container

• variable shape

• variable volume

C. FOUR STATES OF MATTER• Plasma

• very high KE - particles collide with enough energy to break into charged particles (+/-)

• gas-like, variable shape & volume

• stars, fluorescent light bulbs

D. TEMPERATURE

• Heat or thermal energy - total random kinetic energy of the particles.

• Heat flows from a hot object to a cold object. For example: can of soda

• Temperature – measure of the average random kinetic energy of the particles.

D. TEMPERATURE

• SI unit of temp: Kelvin (K)

• The zero point on the Kelvin scale is called absolute zero (the point at which the motion of particles ceases).

0 K = -273.15 oC

( no degree symbol and no negative numbers on the Kelvin scale because there is no negative motion! )

D. TEMPERATURE• Formulas:

oC = K – 273 or K = oC + 273

D. TEMPERATUREoF = (9/5)oC + 32

oC = 5/9 (oF – 32)

E. ENERGY UNITS

• SI unit of energy: joule (J)

• 1J = energy needed to lift a medium apple 1m against gravity

• 1500 J = energy needed to climb an average flight of stairs

E. ENERGY UNITS

• calorie (cal) : unit of energy

• 1 cal = amount of heat needed to raise the temperature of 1g of water, 1oC.

•Conversion factor: 1 cal = 4.184 J

• If it takes 1500 J to climb a set of stairs, calculate how many cal this is.

G. ENERGY UNITS

• 1 cal does not equal 1 Cal !

• Calorie (capital C) is the energy stored in food!• 1 Cal = 1000 cal or 1 kcal• So 200 Cal (a candy bar) supplies 200,000 cal of

energy!

• How many J is this? Calculate. How many times do you have to go up and down the stairs?!

H. HEAT

• Specific heat capacity (c): the amount of heat needed to raise the temperature of 1.0 g of a substance 10C .

• Water has a high specific heat!

• 4.184 J/g0C

H. HEAT• To calculate the heat (energy) released from a

substance:

• q= m Δ t c

Heat released

m= massc= specific heat t = change in temperature