Thermochemistry: heat transfer - Nova Southeastern...
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Shanbhag 2300probset7 1 Thermochemistry: heat transfer Thermochemistry: heat transfer Thermochemistry: heat transfer Thermochemistry: heat transfer An assumption is made that appropriate specific heat and latent heat values are sought from An assumption is made that appropriate specific heat and latent heat values are sought from An assumption is made that appropriate specific heat and latent heat values are sought from An assumption is made that appropriate specific heat and latent heat values are sought from appropriate sources appropriate sources appropriate sources appropriate sources 1. I wish to boil water in a coffee cup. How many calories (and joules) of heat is needed to convert 180 g of water from 15 o C to 96 o C? 2. The heat from condensation of 124 g of steam at 100 o C is used to warm up air in a room 20'x12'x8', (6.44x 10 4 g of air). Under normal conditions the specific heat of air is 1.015 J/g o C What is the change in air temperature? (assume no loss elsewhere) 3. When ice melts, it needs to absorb heat from its surroundings. If an ice cube (15 g) at 0 oC is completely melted when placed in a cup of water (180 g) at 21 o C, what is the final temperature of water? The heat capacity of the cup is 100 J/ o C 4. A 6.22 kg piece of copper metal is heated from 20.5 o C to 324.3 o C. How many kJ of heat are absorbed by the metal? 5. A sheet of gold weighing 10.0 g at 18.0 o C is placed flat on a sheet of iron weighing 20.0 g and at 55.6 o C. What is the temperature of combined metals when a thermal equilibrium has been achieved. (assume no loss elsewhere) 6. A 0.1375 g of Mg is burned in a bomb calorimeter of heat capacity 1.769 kJ/ o C. The calorimeter contains 300 g water. The process produces a 1.126 o C temperature jump. Calculate the heat given out by burning Mg in kJ/g, kCal/mol and kJ/mol 7. Determine the amount of heat released when 5 g Iron at 280 o C is cooled to 275 K. 8. The specific heat of a metal is determined by calorimetry. A 25.00 g of this metal is heated to 165 o C and dropped in a calorimeter that contained 200 g of water at 21.6 o C. After thermal equilibrium, the temperature of water is 23.9 o C. The calorimeter has a heat capacity of 95 J/ o C. Determine the specific heat of the metal 9. Determine the energy involved when 100 g ice at -20 o C is converted to steam at 145 o C. 10. The label on my "Quick Grits" box indicates that per serving 130 calories (food!) of energy is delivered. I want to carry out the bomb calorimetry on grits worth 2 servings. The calorimeter has a heat capacity of 0.892 kJ/ o C and containd 2000 g of water at 20.0 o C. Determine the final temperature of water after the complete combustion process. 11. A 35 mL of water at 87.6 o C is added to 56 mL of water at 21.3 o C. If the heat capacity of the container where mixing was done is 89 J/ o C, What is the expected final temperature/
Transcript of Thermochemistry: heat transfer - Nova Southeastern...
Shanbhag 2300probset7
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Thermochemistry: heat transferThermochemistry: heat transferThermochemistry: heat transferThermochemistry: heat transfer An assumption is made that appropriate specific heat and latent heat values are sought from An assumption is made that appropriate specific heat and latent heat values are sought from An assumption is made that appropriate specific heat and latent heat values are sought from An assumption is made that appropriate specific heat and latent heat values are sought from appropriate sourcesappropriate sourcesappropriate sourcesappropriate sources
1. I wish to boil water in a coffee cup. How many calories (and joules) of heat is needed to convert 180 g of water from 15 oC to 96 oC?
2. The heat from condensation of 124 g of steam at 100 oC is used to warm up air in a room 20'x12'x8', (6.44x 10 4 g of air). Under normal conditions the specific heat of air is 1.015 J/g oC What is the change in air temperature? (assume no loss elsewhere)
3. When ice melts, it needs to absorb heat from its surroundings. If an ice cube (15 g) at 0 oC is completely melted when placed in a cup of water (180 g) at 21 oC, what is the final temperature of water? The heat capacity of the cup is 100 J/oC
4. A 6.22 kg piece of copper metal is heated from 20.5 oC to 324.3 oC. How many kJ of heat are absorbed by the metal?
5. A sheet of gold weighing 10.0 g at 18.0 oC is placed flat on a sheet of iron weighing 20.0 g and at 55.6 oC. What is the temperature of combined metals when a thermal equilibrium has been achieved. (assume no loss elsewhere)
6. A 0.1375 g of Mg is burned in a bomb calorimeter of heat capacity 1.769 kJ/oC. The calorimeter contains 300 g water. The process produces a 1.126 oC temperature jump. Calculate the heat given out by burning Mg in kJ/g, kCal/mol and kJ/mol
7. Determine the amount of heat released when 5 g Iron at 280 oC is cooled to 275 K. 8. The specific heat of a metal is determined by calorimetry. A 25.00 g of this metal is heated
to 165 oC and dropped in a calorimeter that contained 200 g of water at 21.6 oC. After thermal equilibrium, the temperature of water is 23.9 oC. The calorimeter has a heat capacity of 95 J/oC. Determine the specific heat of the metal
9. Determine the energy involved when 100 g ice at -20 oC is converted to steam at 145 oC. 10. The label on my "Quick Grits" box indicates that per serving 130 calories (food!) of energy is
delivered. I want to carry out the bomb calorimetry on grits worth 2 servings. The calorimeter has a heat capacity of 0.892 kJ/oC and containd 2000 g of water at 20.0 oC. Determine the final temperature of water after the complete combustion process.
11. A 35 mL of water at 87.6 oC is added to 56 mL of water at 21.3 oC. If the heat capacity of the container where mixing was done is 89 J/oC, What is the expected final temperature/
Shanbhag 2300probset7
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12. A 505 g piece of copper tubing is heated to 99.9 oC and placed in an insulated vessel containing 59.8 g waterat 24.8 oC. If the heat capacity of the vessel is 10 J/K, what is the final temperature of the system.
13. Pioneers sometimes heated their coffee by placing iron poker from fire directly in coffee. If a cup held 0.50 kg coffee at 20 oC, what would be the temperature of coffee when a 502 g iron poker at 800 oC is placed in it. Assume the specific heat of coffee is 4.00 J/g K, no heat is lost elsewhere and no water vaporizes.
14. One piece of copper jewelry at 100 oC has exactly twice the mass of another piece which is at 40 oC. They are placed insde the calorimeter with negligible heat capacity. What is the final temperature in the calorimeter?
15. A 195 g aluminum engine part at an initial temperature of 3.00 oC has to absorb 40 kJ heat. What will be the final temperature?
16. An unknown volume of water at 18.2 oC is added to 24.4 mL of water at 30.0 oC. If the final temperature of the system is 21.5 oC, what was the volume of cold water? Assume negligible loss to surroundings.
17. Two aircraft rivets one of iron, other of copper, placed in a calorimeter. Iron rivet was at 0 oC and weighed 30.0 g and Copper rivet was at 100 oC and weighed 20 g. What is the temperature of the system? Neglect loss to calorimeter.
18. Ehtylene glycol (used as antifreeze/coolant) has a specific heat of 2.42 J/g K. A 27.7 g ethylene glycol loses 588 J of heat. What was the initial temperature if the final temperature was 30.5 oC.
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