Heat and Temperature Heat is a type of energy. All things are made of atoms and the atoms are always moving. Heat is the total kinetic energy of all the atoms in an object. Even cold things, like an ice cube have heat energy… just not a lot!

Thermal energy and temperature are related though DIFFERENT Thermal energy and temperature are related though DIFFERENT. Temperature is the average kinetic energy of the particles of an object. Thermal Energy is the sum total of all of the energy of the particles of an object.

EXAMPLE A bathtub full of water at 100 oF has more thermal energy than a thimble of water at 100 oF. The temperature is the same but the total amount of energy is different. The bathtub has more energy.

THERMAL ENERGY Thermal Energy – the sum of the kinetic and potential energy of microscopic particles in an object. Thermal energy depends on mass and temperature.

Thermal Energy Thermal Energy = “Heat” Energy is the vibration and movement of the atoms and molecules within substances. As an object is heated up, its atoms and molecules move and collide faster.

Thermal Energy Depends on an object’s: Mass  Reason it is different than temperature 2. Temperature 3. Phase (solid, liquid, gas)

Heat Heat can make particles move faster & farther apart, as it gives particles more energy. Before heating After heating

HEAT Objects with slow-moving atoms have LOW heat energy. Objects with fast-moving atoms have HIGH heat energy.

Hot vs Cold Hot: More average kinetic energy Cold: Less average kinetic energy Molecules move very little and slowly Hot: More average kinetic energy Molecules move more and faster http://phet.colorado.edu/en/simulation/gas-properties

HEAT Thermal energy always moves from warmer to cooler objects. Heat is moving energy.

Measuring Heat The unit of heat is the calorie. A calorie is the amount of heat needed to raise 1 gram of pure water 1 degree Celsius. 1000 calories = 1 Calorie (1 kilocalorie). We measure food’s energy in Calories.

Which has more heat energy?

The iceberg! Why? Because although it has a colder temperature, it has more atoms. Although those atoms are at a lower temperature, they have more total heat energy. Remember that heat is the total kinetic energy of all the atoms in an object.

HEAT Heat – TRANSFER of thermal energy due to a temperature difference. Heat flows spontaneously from hot to cold, but never form cold to hot. What about a melting ice cube??? Where’s heat flowing?

TEMPERATURE Particles of matter are in constant motion. This motion relates directly to the state of matter of the object (solids, liquids, or gases). Temperature affects how fast these particles move. The higher the temperature the faster the particles move. Moving particles possess kinetic energy.

Heat Flow Heat flows spontaneously from areas of higher temperature to areas of lower temperature, as the particles bump and give more energy to slower moving particles. It does NOT take energy to happen. This flow of heat warms cool things and cools warm things. This flow also means we can NEVER reach Absolute Zero (0° K), as heat will always warm up what we are trying to cool. BUT we can get close!(we’ve made it to -272.99999999 or so!)

Heat Flow

What about from cold to hot like an air conditioner or refrigerator? Work must be done and process is NOT spontaneous.

WHAT IS A CALORIE? A calorie is another unit for energy One calorie = 4.18 joules One dietary Calorie = 1 kcal or 1000 calories One dietary Calorie = Food labels tell you how much total energy can be obtained from complete combustion (burning) of the food Whenever food is digested, some energy is lost as heat

Heat & Temperature Units of heat are Joules (J) and calories (cal) Units of temperature are Celsius (C), Fahrenheit (F), or Kelvin (K) degrees

Temperature The average kinetic energy of the particles in a substance is called temperature. Adding heat raises the average kinetic energy, and the particles move faster and the temperature goes up.

TEMPERATURE Temperature – measure related to the average kinetic energy of particles in an object Heat and temperature are related but not the same! Obviously, gaining heat or losing heat CAN change the temperature of a substance Adding heat to an object does not necessarily mean an increase in temperature! Huh? Remember phase changes! http://mutuslab.cs.uwindsor.ca/schurko/animations/waterphases/status_water.htm

There are 3 temperature scales FAHREHEIT (F⁰) This is the one used primarily in America. This is the one used by most of the rest of the world and “regular” scientists. This one is used by some scientists. CELSIUS (C⁰) KELVIN (K⁰)

Temperature Scales for pure water at STP Boiling Point Freezing Point Absolute Zero

Thermometers Thermometers work because things expand when they are heated. The more heat energy something has, the more the liquid in the thermometer expands and moves up the tube.