energy kinetic energy = energy of motion. energy potential energy = stored energy 1. energy of...

Energy

Kinetic energy = energy of motion

Energy

Potential energy = stored energy

1. energy of position due to gravity

Energy

Potential energy = stored energy

2. energy stored in

chemical bonds

Law of Conservation of Energy

Energy can not be

created or destroyed,

only converted from

one form to another.

When energy is RELEASED in a chemical reaction, it is called….

EXOTHERMIC

When energy is ABSORBED in a chemical reaction, it is called….

ENDOTHERMIC

Units of Energy

Energy is measured in JOULES

Also in calories or kilocalories (food)

How many calories are in a kilocalorie?

Units of Energy

How many calories in the hamburger?

420 kilocalories

What is temperature?

A measure of the average kinetic energy of the particles in a sample of matter.

All atoms are moving!

High temperature = moving faster

Once again……

TEMPERATURE

=

AVERAGE KINETIC ENERGY

Temperature Scales

Celcius:

water freezes water boils Zero degrees100 degrees

Temperature Scales

Kelvin: 0 K = absolute zero (-460 oF)all motion of particles stops!

Water freezes @ 273 KWater boils @ 373 K

Kelvin never goes below zero (no negative numbers!)

Temperature Scales

Kelvin = Celsius + 273

Celsius = Kelvin – 273

If it is 32O Celsius, what temperature is it in Kelvin?

If it is 100 Kelvin, what temperature is it in Celsius?

Temperature Scales

Standard Temperature

0 degrees Celsius

273 Kelvin

(in Table A)

At what temperature does liquid nitrogen boil?

• 77 Kelvin

• -195 Celsius

• -320 Farenheit

What is Heat?

Heat is the sum total of all the kinetic energy in a sample of matter.

How is heat different from temperature???

Heat ≠ Temperature

Both the water in the bath tub and in the cup are at 25 oC

Which contains more HEAT?

Heat Capacity

The amount of energy (in JOULES) needed to raise the temperature of the sample by 1 oC

Which water sample has a higher heat capacity?

Specific Heat Capacity

The amount of energy (in JOULES) needed to raise the temperature of 1 gram of the sample by 1 oC

Which water sample has a higher specific heat ?

Specific Heat

Specific heat measures how easily something can absorb (or then lose) heat.

LOW specific heat = little energy for something to

heat up.HIGH specific heat = lots of energy to heat

something up

Every substance has its own unique specific heat value.

Specific Heat Capacity

In your experience, which substance below has a higher specific heat capacity (takes more energy to heat it up?)