Page 136 - 9780077418427.pdf

/Users/user-f465/Desktop
tiL12214_ch04_085-114.indd Page 113 9/1/10 9:38 PM user-f465
tiL12214_ch04_085-114.indd Page 113 9/1/10 9:38 PM user-f465 /Users/user-f465/Desktop

Group A—Continued Group B—Continued
7. A sample of silver at 20.0°C is warmed to 100.0°C when 896 cal is 7. If the silver spoon placed in the coffee in exercise 6 causes
added. What is the mass of the silver? (c silver = 0.056 kcal/kgC°) it to cool 0.75°C, what is the mass of the coffee?
(Assume c coffee = 1.0 cal/gC°.)
8. A 300.0 W immersion heater is used to heat 250.0 g of water 8. How many minutes would be required for a 300.0 W immersion
from 10.0°C to 70.0°C. About how many minutes did this take? heater to heat 250.0 g of water from 20.0°C to 100.0°C?
9. A 100.0 g sample of metal is warmed 20.0°C when 60.0 cal is 9. A 200.0 g china serving bowl is warmed 65.0°C when it absorbs
added. What is the specific heat of this metal? 2.6 kcal of heat from a serving of hot food. What is the specific
heat of the china dish?
10. How much heat is needed to change 250.0 g of ice at 0°C to water 10. A 1.00 kg block of ice at 0°C is added to a picnic cooler. How
at 0°C? much heat will the ice remove as it melts to water at 0°C?
11. How much heat is needed to change 250.0 g of water at 80.0°C to 11. A 500.0 g pot of water at room temperature (20.0°C) is placed on
steam at 100.0°C? a stove. How much heat is required to change this water to steam
at 100.0°C?
12. A 100.0 g sample of water at 20.0°C is heated to steam at 125.0°C. 12. Spent steam from an electric generating plant leaves the turbines
How much heat was absorbed? at 120.0°C and is cooled to 90.0°C liquid water by water from a
cooling tower in a heat exchanger. How much heat is removed by
the cooling tower water for each kg of spent steam?
13. In an electric freezer, 400.0 g of water at 18.0°C is cooled and 13. Lead is a soft, dense metal with a specific heat of 0.028 kcal/kgC°,
frozen, and the ice is chilled to –5.00°C. (a) How much total heat a melting point of 328.0°C, and a heat of fusion of 5.5 kcal/kg.
was removed from the water? (b) If the latent heat of How much heat must be provided to melt a 250.0 kg sample of
vaporization of the Freon refrigerant is 40.0 cal/g, how many lead with a temperature of 20.0°C?
grams of Freon must be evaporated to absorb this heat?
14. A heat engine is supplied with 300.0 cal and rejects 200.0 cal in 14. A heat engine converts 100.0 cal from a supply of 400.0 cal into
the exhaust. How many joules of mechanical work was done? work. How much mechanical work was done?
15. A refrigerator removes 40.0 kcal of heat from the freezer and 15. A heat pump releases 60.0 kcal as it removes 40.0 kcal at the
releases 55.0 kcal through the condenser on the back. How much evaporator coils. How much work does this heat pump ideally
work was done by the compressor? accomplish?

4-29 CHAPTER 4 Heat and Temperature 113