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Objectives: Gas Laws Temperature Heat and Heat Transfer Thermal Expansion
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Celsius (C) Centigrade Kelvin (K) Fahrenheit (F) Related to how fast atoms/molecules are moving (Kinetic Energy)
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Celsius (C) Centigrade Kelvin (K) Water boils Water freezes 100 intervals (degrees) Fahrenheit (F) 0 o C 100 o C Related to how fast atoms/molecules are moving (Kinetic Energy)
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Celsius (C) Centigrade Kelvin (K) Water boils Water freezes 100 intervals (degrees) Fahrenheit (F) 0 o C 100 o C 32 o F 212 o F http://www.wbuf.noaa.gov/tempfc.htm 273 K 373 K Related to how fast atoms/molecules are moving (Kinetic Energy)
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Celsius (C) Centigrade Kelvin (K) Water boils Water freezes 100 intervals (degrees) Fahrenheit (F) 0 o C 100 o C 32 o F 212 o F http://www.wbuf.noaa.gov/tempfc.htm Absolute Zero -273 o C 273 K 0 K 373 K Molecules and Atoms stop moving (no kinetic energy) Related to how fast atoms/molecules are moving (Kinetic Energy) -459 o F
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(Pressure) 1 (Pressure) 2 Boyle’s Law (Volume) 1 (Volume) 2 = Q1. How can we maintain constant temperature? Temperature remains constant!
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(Pressure) 1 (Pressure) 2 Boyle’s Law (Volume) 1 (Volume) 2 = Q1. How can we maintain constant temperature? Temperature remains constant! Ans. Something happens slow! It exchanges heat with the surrounding environment and maintains that temperature Q2. You measure the volume of a gas to be 12 mL at 0.01 PSI. Then you let the gas expand slowly to 18 mL. What would be the pressure? (Pressure) 1 (Pressure) 2 (Volume) 1 (Volume) 2 =
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(Pressure) 1 (Pressure) 2 Gay Lussac Law (Temperature) 1 (Temperature) 2 = Q3. How can we maintain constant volume? Volume remains constant!
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(Pressure) 1 (Pressure) 2 Charle’s Law (Temperature) 1 (Temperature) 2 = Q3. How can we maintain constant volume? Volume remains constant! Ans. Sealed container Q4. The pressure at 300 K is 0.02 PSI. What is the pressure at 600 K? Charle’s Law Requires Kelvin (no Celsius! No Fahrenheit!) (Pressure) 1 (Pressure) 2 (Temperature) 1 (Temperature) 2 =
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(Pressure) 1 (Pressure) 2 Charle’s Law (Temperature) 1 (Temperature) 2 = Q3. How can we maintain constant volume? Volume remains constant! Ans. Sealed container Q4. The pressure at 300 K is 0.02 PSI. What is the pressure at 600 K? Charle’s Law Requires Kelvin (no Celsius! No Fahrenheit!) (0.02 PSI) 1 (Pressure) 2 (300 K) 1 (600 K) 2 =
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20 P1. What is 70 F in Centigrade? Ans. P2. You seal a gas in a container. If you double the temperature of the gas, what happens to the pressure inside? Ans. P3. In the Boyle’s Law (keeping temperature constant), if you triple the pressure, what happens to the volume of the gas. Ans. P4. For a gas sealed in a container, you measure its temperature and pressure to be 300 K and 0.2 PSI. What happens to the pressure if you increase the temperature to 350 K?
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1 BTUHeat required to warm 1 lb water by 1F at sea level. 1 calHeat required to warm 1 g water by 1 o C 1 CalHeat required to warm 1000 g water by 1 o C Q5. How many calories are necessary to heat 50 g of water by 1 o C
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1 BTUHeat required to warm 1 lb water by 1F at sea level. 1 calHeat required to warm 1 g water by 1 o C 1 CalHeat required to warm 1000 g water by 1 o C Q5. How many calories are necessary to heat 50 g of water by 1 o C Q6. How many calories are necessary to heat 50 g of water by 10 o C? (Heat)= (50 g) (1 cal)
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1 BTUHeat required to warm 1 lb water by 1F at sea level. 1 calHeat required to warm 1 g water by 1 o C 1 CalHeat required to warm 1000 g water by 1 o C Q5. How many calories are necessary to heat 50 g of water by 1 o C Q6. How many calories are necessary to heat 50 g of water by 10 o C? (Heat) (10 o C) = (50 g) (1 cal) (Heat)= (50 g) (1 cal)
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1 BTUHeat required to warm 1 lb water by 1F at sea level. 1 calHeat required to warm 1 g water by 1 o C 1 CalHeat required to warm 1000 g water by 1 o C Q6. How many calories are necessary to heat 50 g of water by 10 o C Q7. How many calories are necessary to heat 50 g of iron by 10 o C? (10 o C) (Heat)= (50 g) (??? cal) (10 o C) (Heat)= (50 g) (1 cal)
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1 BTUHeat required to warm 1 lb water by 1F at sea level. 1 calHeat required to warm 1 g water by 1 o C 1 CalHeat required to warm 1000 g water by 1 o C Q6. How many calories are necessary to heat 50 g of water by 10 o C Q7. How many calories are necessary to heat 50 g of iron by 10 o C? (10 o C) (Heat)= (50 g) (??? cal) (10 o C) (Heat)= (50 g) (1 cal) Specific heat0.108 cal/g
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Q8. How many Btus are required to heat up 5.0 lb of iron by 10 F? (temperature change)(Heat)= (mass) (specific heat)
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Q8. How many Btus are required to heat up 5.0 lb of iron by 10 F? (temperature change)(Heat)= (mass) (specific heat) (10 o F) (Heat)= (5.0 lb) (0.11 Btu/g.F)
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Vapor
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Q1. What is the melting point for ice? Vapor
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Q1. What is the melting point for ice? Q2. What is the condensation point for water vapor? Vapor
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Convection Mixing (requires air or other mixing particles) Examples: warming soup on stove top
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Convection Conduction Mixing (requires air or other mixing particles) Direct Contact Examples: warming soup on stove top Examples: tip of a needle over flame
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Convection Conduction Radiation Mixing (requires air or other mixing particles) No substance required Direct Contact Examples: warming soup on stove top Examples: tip of a needle over flame Examples: warming soup in the microwave oven, heat coming from the sun
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Linear Volume Railroad tracks, Bridge metal rods Gasoline inside tank As temperature rises, dimensions expand Q9. As you heat a rectangular plate, what happens to its dimensions?
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Linear Volume Railroad tracks, Bridge metal rods Gasoline inside tank As temperature rises, dimensions expand Q9. As you heat a rectangular plate, what happens to its dimensions? Q10. If the plate has a hole, what happens to the dimensions of the hole?
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20 Ans. P1. How many Btus are required to heat 2.0 lb of water by 20 F? P3. You place an ice cube on the stove top and wait until it melts. P4. When does your car tank contain more gasoline? (a) summer (b) winter (c) It doesn’t matter (a) Ice absorbed heat and turned into water (b) Ice released heat and turned into water (c) Ice changed into water without any heat transfer. Ans. P2. How many cal are required to heat 200 g of iron by 5 o C ?
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Heat In Heat Out Work efficiency = Heat In Work Q11. If heat flows in at a rate of 3000 hp, and only 1000 hp is delivered as work, how much energy is wasted? What is the efficiency?
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Heat In (cold inside ) Heat Out (warm room) Work Of el. forces C. P. = Heat In Work Q11. If the fridge removes 200 J from the cold inside, and uses 100 J of electrical force work, how much energy is released in the room? What is its C.P. C. P. – Coefficient of Performance
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P1. The diagram shows the energy flow for an engine. Determine the energy wasted every second and the efficiency of the engine. 20 Engine 2000 hp 800 hp Refrigerator 350 J 200 J P2. The diagram shows the energy flow for a refrigerator. Determine the energy released at the back of the room and the C.P. of the fridge.
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