Heat and Heat and ThermometerThermometer

ELED 4312ELED 4312

Science ContentScience Content

ContentsContents• Why do we need thermometer?• How does a thermometer work?• Change of Matter• Kinetic theory• Heat Energy• Heat Transfer• Scales of Temperature

If there is a no thermometer…If there is a no thermometer…

“How hot is he?”

“How cold is there?”

“I don’t know”

“Here is not cold..I feel pretty hot…”

ThermometerThermometer

• A thermometer is a device that measures the temperature of things.

• To measure the temperature with a

particular scale in order for others to understand the degree of temperature exactly.

How does a thermometer work?How does a thermometer work?

Hot weather!High temperature!

Cold weather!Low temperature!

The Function of ThermometerThe Function of Thermometer

• Thermometers rely on the simple principle that a liquid changes its volume relative to its temperature.

Low temperature

Hightemperature

Liquids(mercury or alcohols)Volume decreases!

Volume increases!

ChangeChange of Matter State of Matter State

Heat Energy Heat Energy

Particles of matters

Kinetic theory of matterKinetic theory of matter• All matter is made up of atoms and molecules

that are constantly moving.

• The motion and spacing of the particles determines the state of matter of the substance.

• When heat is added to a substance, the molecules and atoms vibrate faster. Solids, liquids and gases all expand when heat is added. When heat leaves all substances, the molecules vibrate slower.

• Mass of the object remains the same. “Law of Conservation of Mass”

HeatHeat makes makes the state of matter change!the state of matter change!

In general, the volume of matters increase except water!

Change of State of Matter: Change of State of Matter: Physical ChangePhysical Change

• A physical change does not produce a new substance.

• Changes in state or phase (melting, freezing, vaporization, condensation, sublimation) are physical changes.

• Examples of physical changes include crushing a can, melting an ice cube, and breaking a bottle.

What is Heat Energy?What is Heat Energy?

• The heat energy of a substance is determined by how active its atoms and molecules are.

• A hot object is one whose atoms and molecules are excited and show rapid movement. A cooler object's molecules and atoms will be less excited and show less movement.

• When these atoms and molecules are in the excited state, they take up a lot of space because they're moving around so fast. When the atoms and molecules settle down, or cool down, they take up less space.

Heat TransferHeat Transfer

• Heat travels from a hot object to a cold object.

ConductionConduction

• Conduction is the transfer of thermal energy through direct molecular communication in direct physical contact.

• Conduction is greater in solids, where atoms are in constant contact. Liquids and gases are not good conductors.

ConvectionConvection

• transfer of heat by convection in a moving medium, such as a fluid or gas.

Hot water rises And Cool falls

Heated air rises, cools, thenfalls.  Air near heater isreplaced by cooler air, andthe cycle repeats.

Air above warmer Ground rises.

RadiationRadiation

• Transfer of heat by electromagnetic radiation or, equivalently, by photons.

• All materials radiate thermal energy in amounts determined by

their temperature, where the energy is carried by photons of light. white reflectsradiant energy better than black.

Absorption and Emission of Radiation

Scales of TemperatureScales of Temperature• Fahrenheit scale - Freezing Point of Water: 32 degrees Fahrenheit

- Boiling Point of Water: 212 degrees F. • Celsius scale - Freezing Point of Water: 0 degrees Celsius

- Boiling Point of Water: 100 degrees C. • Kelvin Scale- 0 Degrees of Kelvin: This is at minus 273.15

degrees Celsius (or -523.67 F)!

Temperature ConversionTemperature Conversion

• Celsius = (Fahrenheit – 32)*5/9• Fahrenheit = (Celsius * 9/5)+ 32

• Kelvin = Celsius + 273

29. Which of the following statements 29. Which of the following statements accurately describes what occurs as heat is accurately describes what occurs as heat is added to water and change it to steam?added to water and change it to steam?

A. The water molecules gain kinetic energy and move faster and father apart.

B. The chemical bonds between the hydrogen and oxygen atoms of the water molecules break.

C. The water molecules cluster together to form ring-shaped molecular structures.

D. The hydrogen and oxygen atoms of the water molecules change in shape.

From the sample test of the TExES Preparation Manual

Reference WebsitesReference Websites• Rader’s CHEM4KIDS!http://www.chem4kids.com/index.html

• How atoms and molecules are affected by Heat

http://www.mansfieldct.org/schools/mms/staff/hand/atomsheat.htm

• How Things work!http://www.energyquest.ca.gov/how_it_works/

thermometer.html