Heat

• the thermal Energy that is transferred from one system to another

• –Movement of atoms

  –Total potential and kinetic energy of molecular motion in a substance.

  –Depends on speed, number (size and mass), and type of particles.

  –Transfers between objects

  –Units Joules, Calorie

• symbol is Q, Q = mCΔT

• A large object can have more heat that a small object with a higher temperature. Ex. water trough and hot cup of coffee

Temperature

• a measurement of the average kinetic energy of the particles in a system

• –Thermo =heat

  –Meter = to measure

  –Measurement of the average kinetic energy of molecular motion in a substance.

  –Hotness or coldness

  –Does not depend on the speed or type of particle.

  –Units Celcius, K, F

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Temperature scales and converting

Fahrenheit

Celcius

Kelvin

Celcius

Celsius (⁰ C) is a fundamental unit. One of the original seven. (It was called Centigrade up until the 1950’s.) It was invented in 1742 by A. Celsius, a Swedish astronomer to replace the Fahrenheit scale. The calibrations are set for the freezing and boiling points of water. (Your book makes a big deal about how temperature is expressed in degrees Celsius (⁰C) and to express the change in temperature use Celsius degrees (C⁰)).

Fahrenheit

 Fahrenheit (⁰ F) is the temperature scale we use in the United States. It is credited to G. D. Fahrenheit – German physicist was the first to use Hg in the thermometers.

 Kelvin

 Kelvin (K) Lord Kelvin's scale is related to absolute zero. (Notice there is no degree symbol with the K.) Absolute zero is -273.15⁰ C.

1.     Has scientific significance, in fact is required in some of the heat and thermodynamics problems.

2.     It is now the fundamental unit for heat.

3.     It is not expressed with degrees Kelvin or with Kelvin degrees, the word degrees is not used. 

K = C +273

Temperature Conversions

     C⁰ to F⁰

F⁰ = 9/5C⁰ +32

Ex. 15⁰ C is what in F⁰

F⁰ = 9/5*15 +32

F⁰ = 59⁰

note standard order of operation (no parenthesis)

Temperature Conversions

   F⁰ to C⁰

C = 5/9(F⁰-32)

Ex. 75⁰ F⁰ is what in C

C ⁰= 5/9(75-32)

C⁰ = 24⁰

note order of operation ( parenthesis first!)

Temperature Conversions

   C⁰ to K

K = C +273

Ex. 24⁰ C⁰ is what in K⁰

K = C +273

K = 24⁰ +273

K = 297

This equation is also used to convert K to C

297 = C +273

C = 297-273

C = 24