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## PowerPoint Slideshow about ' Heat ' - tatyana-valdez

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### Heat

The motion of the particles of matter

Heat Transfer

- Heat flows from an area of high heat to an area low in heat.

Three methods of heat transfer

Conduction:

- Transfer from one substance to another by direct contact of molecules. Example: When you touch a hot stove.
- Convection:
- Heat carried from one place to another in a liquid or gas as molecules move in currents caused by density differences. Example: Warm air rising.
- Radiation:
- Heat carried through empty space in the form of infrared rays. Example: When you face the sun and feel warmth on your face.

Temperature:

- A measure of the average kinetic energy of molecules.
- The faster the molecules of a substance are moving, on average, the higher the temperature.
- Thermometer - An instrument for measuring temperature.

How do you set a temperature scale? (watch the videos below!)

- How Fahrenheit made his Temperature scale-
- The Celsius Scale
- Fahrenheit based it on his own body temperature (100°F) and the freezing point of saturated salt water.
- Celsius based it on the boiling point of water (100°C) and the freezing point of water.
- Kelvin has the same degree scale as Celcius, but starts at absolute zero.—no negative temperatures!

Temperature Scales:

- Celsius -
- Most common scale world wide - Used in all scientific measurements.
- Freezing point of water is 0o C.
- Boiling point of water is 100o C.
- Kelvin -
- An "absolute" scale used for kinetic theory calculations.
- Zero on this scale, 0 K, is the lowest possible temperature.
- Note the way the temperature is written, 0 K. This is read as "zero kelvins", without using the word degrees.
- To convert Celsius degrees to kelvins, add 273 to the Celsius temperature.
- Fahrenheit -
- The temperature scale generally used in the United States.
- Freezing point of water is 32 oF.
- Boiling point of water is 212 oF.
- While converting between oC and oF is not stressed in this class, a "ball park" conversion would be oC = (oF - 30) / 2. While this gives a Celsius temperature that is a little low, it is a quick way to compare the two scales.

Absolute Zero

- - The lowest possible temperature.
- The temperature would be 0 K or about -273 oC.

Calorie:

- The unit of heat.
- The amount of heat needed to raise the temperature of one gram of water one degree Celsius.
- A "Food Calorie" is 1000 calories, or a Kilocalorie

Specific Heat

- The ability of a substance to absorb heat.
- Number of calories needed to raise the temperature of one gram of the substance one Celsius degree.
- The units of Specific Heat are - calories per gram Celsius degree.

EQUATION

Q = cm DT

DT = final T – initial T

- Heat gain/lost =(mass) (change in Temp) (spec. heat)
- Specific heat of water

c = 1 calorie/gram°C

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