Radiation

Thermal Expansion

Conduction

Convection

Temperature

Freezing/Boiling Point

What is heat?

How is heat measured?

Heat

What is Heat?

• Heat is a form of energy in moving particles of matter

• As particles move faster, the particles move apart

• Enough heat could be used to boil away the water

Everything is moving?

• Matter is made up of tiny particles in motion

• Matter + Heat = Particles in matter moving faster

• Ex. touching a hot instrument to candle wax

Heat and Work

• Heat can cause particles in matter to move, therefore heat is able to do work

• What is one example of a machine that is powered by heat?

Measuring Heat

• Heat is measured as a Calorie (c)

• One calorie is the amount of heat needed to raise the temp of 1g or water, 1 °C

• One gram is a small amount of water; One calorie is a small amount of heat

Food Energy

• Food contains Calories (C) as well

• Food calories are represented with a capital C

• The food calorie contain 1000 calories, enough to raise 1000 grams of water, 1°C

Calories in Food• Table 1 Calories in Food FOOD AMOUNT CALORIES• Apple 1 medium 70• Banana 1 large 200• Bread, white 1 slice 60• Butter 1 pat 50• Celery 1 stalk 3• Chili w/ beans 8 oz. 290• Corn flakes 1 cup 95• Egg, fried 1 110• Green beans ½ cup 15• Hamburger, with roll ¼ lb 320• Milk, whole 8 oz. 160• Pizza 1 slice 240• Potato chips 1 13• Potatoes, french fried 10 150• Gasoline 1 gallon 31,000,000

Why do calories cause weight gain?

• Calories are stored in foods that contain a high potential energy

• Foods like potato chips, hamburgers, french fries contain a high percentage of fat, or flammable material.

• That is why you can “burn” calories to loose weight!!!

CheckPoint!!

1. Adding heat energy to particles of matter, causes those particles to move ___________.

2. Is heat a form of kinetic or potential energy? Explain.

3. Describe what happens when you add ice cubes to a glass of warm water.

4. What is the difference between Calories (c) and (C)?

5. Explain how calories in different foods can cause weight gain.

Temperature and Heat

• Temp and Heat are NOT the same

• Temperature is a measure of the average kinetic energy of a substance

• Adding/removing heat to a substance will change the temperature

Absolute Zero

•As heat is removed from a substance, the particles begin to move slower

•When all particle motion stops, absolute zero has been reached

•Absolute Zero = -273°C

Freezing Point

• Temp at which a liquid turns solid

• Water begins to freeze at 0°C

• The temperature of ice can drop below 0°C

Freezing of Water

Time Temp

0 min 22° C

5 min 15° C

10 min 10° C

15 min 6° C

20 min 3° C

25 min 0° C

30 min 0° C

35 min 0° C

Freezing Point, cont.

• Not every liquid begins freezing at 0° C

Freezing Points of Liquids

Liquid Freezing Point

Water 0° C

Ethyl alcohol -117° C

Mercury -39.8° C

Sea water -1.9° C

Glycerine 18° C

Melting Point

• Temperature when a solid turns into a liquid

• Melting and Freezing points are often the same

• The melting point of ice is 0°C

Sublime

• Sublimination – Is when a substance changes directly from a solid to a gas

• Example: Dry Ice

• Dry ice can keep objects frozen, without the mess of melting

Boiling Point

• Temperature when a liquid turns to a gas

• Evaporation occurs on the surface of the liquid

• What temperature does water boil at?

Boiling Points

Boiling Points of Liquids

LIQUID BOILING POINT

Water 100° C

Mercury 357° C

Glycerine 290° C

Acetic acid 118° C

Benzene 80° C

Ethyl alcohol 78° C

Acetone 39° C

Check Point!1. Use the internet to research and find the highest

and lowest documented temperature on Earth.2. What happens to the particles in water when it

reaches 0°C?3. If an object changes directly from solid to gas, this

process is called_________.4. An uncovered liquid changes to a gas at room

temperature by the process of ____________.5. Which of the liquids we have studied have the

lowest boiling point?6. The engine in your car uses water to keep from

overheating in the summer. What is mixed with water during the winter months to keep your engine from freezing and cracking?