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The Assessment Solved:
1. What is the melting temperature and the boiling temperature of this substance? Label the solid, liquid and gaseous phases.
(Melt = 30 oC, Boil = 50 oC, solid 0-300 J added, Liquid 700-1100 J added, Gas 1700-2000 J added.)
2. What is the latent heat of vaporisation? (Boiling)
(2750 J/kg)
3. What is the specific heat of the liquid phase?
(91.7 J/kgoC)
4. What heat do you need to heat 3.29 Kg of water at 21.0 oC to steam at 175 oC? (For H2O: Cice = 2100 J/kgoC, lf = 3.33 x 105 J/Kg, Cwater = 4186 J/KgoC, lv = 22.6 x 105 J/Kg, Csteam = 2010 J/kgoC)
(9.02 x 106 J)
This one seems to be the hardest on this assessment - here is another:
5. 500. grams of a mystery liquid at 45.0 oC is mixed with 300. grams of water (C = 4186 J/KgoC) initially at 22.0 oC. The final temperature of the mixture is 33.0 oC. What is the specific heat of the mystery liquid? (Assuming no heat was lost to the surroundings)
(2.30 x 103 J/kgoC)
Worksheet 14A: Specific Heat, Latent Heat, Phase Change Graphs, and Calorimetry
Objective A: Caloric and Joule’s discovery
Questions:
1. What was the caloric model?
2. How did it fail to explain the heating of drill bits when they got dull?
Objective B: Specific Heat: Q = mCdT
Questions:
3. What is the specific heat of a substance? What does it mean?
Problems:
4. What heat is needed to raise 3.4 kg of lead from 23 oC to 58 oC? (1.5E4 J) Video
5. If 23.0 kg of copper at 21.0 oC absorbs 45.6 kJ of heat, what will be its final temperature? (26.1 oC) Video
6. If some aluminum at 57.0 oC, cools to 24.1 oC, and gives off 13.4 kJ of heat, what is its mass? (453 g) Video
7. A 35.0 g of a mystery substance absorbs 314 J of heat and raises its temperature by 2.14 oC. What is its specific heat? (4190 JoC-1kg-1) Video
8. A 125 Watt 100% efficient heater is immersed in a 503 ml container full of water. In what time will the heater heat the water from 21.0 oC to boiling? (1330 s) Video
9. Another 1250 Watt heater can raise 2.35 liters of water from 14.5 oC to 36.6 oC in three and a half minutes. What is its efficiency? (.828 or 82.8%) Video
Objective C: Latent Heat: Q = mL
Questions:
10. What is the latent heat of a substance? What does it mean?
11. Why is the latent heat of vaporization almost always more?
Problems:
12. What heat does it take to melt 25 kg of solid iron already at the melting point? (7.2E6 J) Video
13. 2350 J of heat will melt how much lead? (94 g) Video
14. If it takes 45,120 J of heat to melt 172 g of a mystery substance, what is its latent heat of fusion? (2.62E5 J/kg) Video
15. A runner sweats away 3.5 kg of water through evaporation. What heat did they dissipate? (7.9E6 J) Video
16. What heat do you need to heat 2.15 Kg of ice at -34.0 oC to water at 75.0 oC? (1.54x106 J)
17. What heat do you need to heat 23.5 Kg of ice at -167.0 oC to water at 92.0 oC? (2.51x107 J) Video
18. What heat do you need to heat 3.61 Kg of water at 76.0 oC to steam at 142 oC? (8.83x106 J) Video
Objective E: Calorimetry: Heat Lost = Heat Gained
Problems:
19. 112. grams of a mystery liquid at 83.0 oC is mixed with 564 grams of water initially at 22.0 oC. The final temperature of the mixture is 33.0 oC. What is the specific heat of the mystery liquid? (Assuming no heat was lost to the surroundings) (4640 J kg-1 oC-1) Video
20. A piece of lead (c = 130 J/kg/oC) at 82.0 oC is mixed with 112 grams of water and an 87.5 g aluminum (c = 900. J/kg/oC) calorimeter cup initially at 25.0 oC. The final temperature of the system is 56.0 oC. What is the mass of the piece of lead? (Assuming no heat was lost to the surroundings) (5.02 kg) Video
21. 89.2 g of a mystery substance is at 99.20 oC, and it is placed in a 95.0 g iron container holding 216 ml of water both at 21.01 oC. The final temperature is 23.38 oC. What is the specific heat of the substance? (332 J/kg/oC) Video
22. A 347 g piece of copper at 98.0 oC is placed in a Styrofoam cup containing 259 ml of water at 18.0 oC. What will be the final temperature of equilibrium? (Ignore the Styrofoam) (26.9 oC) Video
23. A 13.5 g piece of aluminum at 93.9 oC is placed in an 82.0 g iron calorimeter containing 203 g of water both at 23.0 oC. What will be the final temperature? (24.0 oC) Video
24. If you drop a 16 g ice cube at 0.0 oC into a Styrofoam cup containing 241 ml of water at 20.0 oC what will be the final temperature? (13.8 oC)
25. You take an ice cube out of the freezer at -17.0 oC, and drop it into a 67.0 g aluminum cup containing 308 g of water at 23.0 oC. The final temperature is observed to be 12.7 oC. What is the mass of the ice cube? (33.0 g)
Objective D: Phase change graphs
Here is a phase change graph for 0.0160 kg of a substance that starts out as a solid at 0 oC:
26. Label the graph where the KE is increasing, and where the PE is increasing. Video
27. What is the melting point? What is the boiling point? (30. oC, 80. oC) Video
28. What is the specific heat of the solid, liquid and gas phase? (104 J/kg/oC, 188 J/kg/oC, 156 J/kg/oC) Video
29. What is the latent heat of fusion and vaporisation? (9380 J/kg, 15,600 J/kg) Video
Here is another phase change graph for 0.026 kg of a substance that starts out as a solid at 0 oC:
30. Label the graph where the KE is increasing, and where the PE is increasing. Video
31. What is the melting point? What is the boiling point? (40. oC, 80. oC) Video
32. What is the specific heat of the solid, liquid and gas phase? (48.1 J/kg/oC, 240. J/kg/oC, 76.9 J/kg/oC) Video
33. What is the latent heat of fusion and vaporisation? (7,690 J/kg, 11,500 J/kg) Video
Instruction: for this unit
Specific and Latent heat:
5:34 Solving Calorimetry Problems
Solving for the final temperature:
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