SECTION 10-1SECTION 10-1

TEMPERATURETEMPERATURE

A.A. Temperature and Temperature and EnergyEnergy

Temperature: Temperature: Def. p.324Def. p.324

In our everyday In our everyday life, we associate life, we associate the sensation of the sensation of hot or cold with the hot or cold with the temperature of an temperature of an object.object.

Every moving Every moving particle has kinetic particle has kinetic energy, the energy, the average of the average of the kinetic energy of kinetic energy of the moving particle the moving particle is called is called temperature.temperature.

If the average Kinetic If the average Kinetic energy of an object energy of an object increases so does the increases so does the object’s temperature object’s temperature and vice-versa.and vice-versa.

The easiest way to The easiest way to measure temperature measure temperature is with a thermometer. is with a thermometer.

Thermometer:Thermometer: Def. Def. p.325.p.325.

i.i. Common Common Thermometers rely Thermometers rely on expansionon expansion..

This is because most This is because most objects expand when objects expand when they are hot.they are hot.

Thermometers use this Thermometers use this physical prop. of physical prop. of expansion, ex. liquid expansion, ex. liquid mercury and colored mercury and colored alcohol used in alcohol used in thermometers expand thermometers expand when the temperature when the temperature increases and increases and contracts when contracts when temperature drops.temperature drops.

The expansion and The expansion and contraction is the contraction is the result of energy result of energy exchange between exchange between the thermometer the thermometer and the and the surroundings.surroundings.

Liquid Liquid thermometers thermometers measure only measure only temperature within temperature within a certain range: a certain range: below certain below certain temperature it temperature it freezes and above freezes and above certain certain temperature it temperature it expands.expands.

Thermometer in Thermometer in the refrigerator the refrigerator uses the expansion uses the expansion of metal; it of metal; it contains a coil that contains a coil that contains two contains two different metals different metals strips that expand strips that expand and contract as the and contract as the temperature temperature changes.changes.

ii.ii. Fahrenheit and Fahrenheit and Celsius are common Celsius are common scales used for scales used for measuring measuring temperature.temperature.

In the US, the most In the US, the most familiar temperature familiar temperature scale is the Fahrenheit scale is the Fahrenheit scale.scale.

The units on the The units on the Fahrenheit scale are Fahrenheit scale are called degrees called degrees Fahrenheit or Fahrenheit or ooFF

On the Fahrenheit On the Fahrenheit scale, Hscale, H22O freezes at O freezes at 3232ooF and boils at 212F and boils at 212ooF.F.

Other countries use the Other countries use the Celsius (or Centigrade Celsius (or Centigrade scale). Also used in scale). Also used in science.science.

Freezing point is 0Freezing point is 0ooC C while boiling point is while boiling point is 100100ooC.C.

Degree Celsius is Degree Celsius is nearly twice as nearly twice as large as degree large as degree Fahrenheit.Fahrenheit.

To convert Celsius To convert Celsius to Fahrenheit or to Fahrenheit or Fahrenheit to Fahrenheit to Celsius, pg.326. Celsius, pg.326. (Equation)(Equation)

iii.iii. The Kelvin The Kelvin scale is based scale is based on absolute on absolute zero.zero.

Lowest Lowest temperature temperature physically possible physically possible is -273.13is -273.13ooC. This C. This is referred to as is referred to as absolute zeroabsolute zero..

Absolute zeroAbsolute zero: : Def. p.327.Def. p.327.

Absolute zero is the Absolute zero is the basis for the Kelvin basis for the Kelvin scale. The lowest scale. The lowest temperature this temperature this scale is Ok hence scale is Ok hence the Kelvin scale has the Kelvin scale has no negative value.no negative value.

The Celsius - The Celsius - Kelvin equation = Kelvin equation = p.327p.327..

CONVERSION EQUATIONSCONVERSION EQUATIONS

°C to °F = 9/5 × (°C) + 32°C to °F = 9/5 × (°C) + 32K to °F = 9/5(°K - 273) + 32K to °F = 9/5(°K - 273) + 32°F to °C = 5/9(°F - 32)°F to °C = 5/9(°F - 32)°C to K = °C + 273°C to K = °C + 273°F to K = 5/9 (°F - 32) + 273°F to K = 5/9 (°F - 32) + 273

B.B. Relating Temperature to Relating Temperature to Energy Transfer as Heat.Energy Transfer as Heat.

i.i. The feeling The feeling associated with associated with temperature temperature difference results difference results from energy transfer.from energy transfer.

HeatHeat: Def. p.330.: Def. p.330. Transfer of energy Transfer of energy

always goes from a always goes from a substance at a higher substance at a higher temperature to a temperature to a substance at a lowest substance at a lowest temperature.temperature.