What is heat? How is heat measured? Temperature Freezing/Boiling Point Conduction Convection Radiation Thermal Expansion 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 Apple1 medium70 Banana1 large200 Bread, white1 slice60 Butter1 pat50 Celery1 stalk3 Chili w/ beans8 oz.290 Corn flakes1 cup95 Egg, fried1110 Green beans½ cup15 Hamburger, with roll¼ lb320 Milk, whole8 oz.160 Pizza1 slice240 Potato chips113 Potatoes, french fried10150 Gasoline1 gallon31,000,000

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 min22° C 5 min15° C 10 min10° C 15 min6° C 20 min3° C 25 min0° C 30 min0° C 35 min0° C

Freezing Point, cont. Not every liquid begins freezing at 0° C Freezing Points of Liquids Liquid Freezing Point Water0° C Ethyl alcohol-117° C Mercury-39.8° C Sea water-1.9° C Glycerine18° 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 Water100° C Mercury357° C Glycerine290° C Acetic acid118° C Benzene80° C Ethyl alcohol78° C Acetone39° 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?