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# Thermodynamics PowerPoint PPT Presentation

Thermodynamics. 6E, 6F, 6G. IAN 51. Radiant Energy- CER Will there be a difference in temperature between a dark cup and a light cup?. Claim Evidence Reasoning. IAN 56. Temperature . Incomplete. True or false: Temperature is the degree of coldness or hotness of an object

Thermodynamics

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## Thermodynamics

6E, 6F, 6G

IAN 51

• Claim

• Evidence

• Reasoning

IAN 56

### Temperature

Incomplete

• True or false: Temperature is the degree of coldness or hotness of an object

• Hotness and coldness are relative terms

• Temperature is a measure of the average kinetic energy of the molecules of a substance

• Which is hotter if both are boiling?

Neither. Both at same temperature, which is the avg. KE.

Tub has more burning effect b/c it has more surface area

### Units of Temperature

• Fahrenheit & Celsius

• Celsius& Kelvin

• Absolute zero- lowest temperature where atoms transfer no thermal energy

IAN 56

### Thermal Equilibrium

20◦

10◦

• Thermal= heat

• Thermal Equilibrium- the net flow of heat = zero

• Heat- process of thermal energy transfer as a result of temperature difference

• No object has heat, but it feels heat

• Heat transfers, cold does not

Remember the Law of Conservation of Energy: Energy is neither created nor destroyed. Its transferred from one form to another.

### Heat Transfer Notes

• Solids- conduction (think metals)

• Fluids (liquids/ gases)- convection

• no contact- radiation (think sun)

### Insulators vs. Conductors

Insulators

Conductors

Transfer heat

Metals

Ex. copper wires, forks, jewelry, etc.

• Absorb heat

• Non-metals

• Dark colors

• Ex. coat filling, plastic sheath around wires, and Styrofoam cup

### Laws of Thermodynamics NotesEndo- vs. Exo- thermic

IAN 52

• Thermal= heat, dynamics= energy or force

• 1st Law- the internal energy (∆U) of a system can either be increased by adding heat (Q) or doing work (W)

• 2nd Law- heat will travel from hot to cold on its own and never from cold to hot causing an increase in entropy (or disorder)

### Specific Heat∆Q=mc∆T

• Q= heat gained or lost

• c= specific heat

• T= temperature (°C)

• Specific heat- amount of heat required to raise 1 kg of a substance a temperature of 1 K

• Units for heat

• 1 BTU=1055 J

• 1 cal= 4.184 J

### Latent Heat

• Thermal expansion- increase in volume due to addition of heat (ex. balloon)

• Heat of fusion (Hf)- amount of heat absorbed during melting/freezing Q=mHf

• Heat of vaporization (Hv)- amount of heat absorbed during evaporation/ condensation Q=mHv

• Why do solids expand or contract when the temp changes?

Q=mHfQ=mHv

IAN 58

### Specific Heat Warm-Up

• 2. Calculate the heat required to raise the temperature of a kitchen pot (made from copper, which has a specific heat capacity of 90 J/kg*K) from 12 ˚C to 111 ˚C. m=

• 3. Calculate the heat required to raise the temperature of water from 1 ˚C to 99 ˚C. The specific heat capacity of water is 4184 J/kg*K.

• 4. Calculate the heat required to raise the temperature of copper from 1 ˚C to 99 ˚C.

• 5.Calculate the heat required to raise the temperature of milk from 4 ˚C to 16 ˚C. The specific heat capacity of milk is 3193 J/kg*K.

### Heat Transfer Visual

• Draw a visual of an example of each mode of heat transfer: conduction, convection & radiation

• Include an explanation of each example

IAN 55

• Claim

• Evidence

• Reasoning

### Penny Experiment

• Penny Experiment

• Materials: glass bottle with opening no larger than a penny, one penny, bowl of ice cold water.

• Dip the penny and the threads of the bottle neck in the cold water. Put the penny over the opening of the bottle and wrap hands around the bottle until the penny jumps. The heat from your hands is transferred through conduction to the air in the bottle warming the air. This causes the air molecules to move faster which makes the penny jump.