1. Temperature and Heat

2. Definition of Temperature  Temperature is proportional to the kinetic energy of atoms and molecules.  For gases, we have translational kinetic energy for the atoms of the gas.  For solids and liquids, we have vibrational or rotational kinetic energy of the atoms.

3. Temperature  It is the measure of the average kinetic energy of all the atoms in a substance.  As energy is given to an object, it is distributed throughout and each particle has an increase in their kinetic energy.  This causes an increase in temperature.

4. Internal Energy  This is the energies associated with atomic motion.  It is proportional to the temperature of the substance.  As the temperature of the substance increases, the internal energy of the substance also increases.

5. Thermal equilibrium  When two objects of different temperatures are in contact they will come to equilibrium at a temperature somewhere between their original temperatures.  It will not be directly in the middle to the two original temperature however.  More on this tomorrow…

6. Thermal Expansion  When substances heat up, they expand.  When substances are cooled, they contract.  How does a thermometer work?

7. Temperature scales  Fahrenheit: Temperature in which brine (salt/water mixture) will freeze is used as the reference point.  0°F is when brine will freeze.  32°F is when water freezes.  212°F is when water boils.

8. Celsius  Celsius uses distilled water as a reference point  0°C is freezing point for water.  100°C is boiling point for water.

9. Conversion between F and C

10. Kelvin Temperature scale  According to Charle’s Law (not done in the CP class), Volume and Temperature are directly related for ideal gases.  As temperature decreases, the volume decreases.  On a graph, using information about a known gas and statistics for how to find a line of best fit, scientists found a temperature that correlates to 0 volume.

11. Kelvin continued  0 K is reffered to as absolute zero.  The closes temperature reached in a laboratory is 0.000001K.  0°C = 273K  Therefore, the conversion is Kevlin Temp = Celsius Temp + 273.

12. Back to Thermal equilibrium  How does temperature change when two objects are in contact?  Energy is transferred.

13. Energy transferred history  Up until the mid-1800’s, scientists believed that energy that caused the change in temperature was due to a fluid called “caloric”.  Until, James Joule showed that the mechanical energy can produce a change in temperature.

14. Heat  The transfer of energy due to a temperature change is called “Heat”.  Heat is measured in units for energy:  Joule  Calorie  Btu (British Thermal Units)

15. Conservation of energy  So, if energy is transferred during a change in temperature, and energy is always conserved…  During a temperature change, the heat lost by an object is gained by its surroundings.  During thermal equilibrium, heat lost is equal to heat gained for the two objects in contact.