A. Sensible Heat
1. How much heat is absorbed by 250.0 g of water when it is heated from 10.0°C to 85.0°C?
2. How much heat is absorbed by 60.0 g of copper when it is heated from 20.0°C to 80.0°C?
3. A 38.0 kg block of lead is heated from -26°C to 180.°C. How much heat does the lead absorb?
4. The cooling system of an automobile engine contains 20.0 L of water. (One liter of water has a mass of one kilogram.) What is the change in temperature of the water if the engine operates until 836.0 kJ of heat are added
5. Suppose the engine in question # 4 was filled with methanol whose density is 0.800 g/cm3. What increase in temperature would occur if the methanol absorbed the same 836.0 kJ of heat? Which is a better coolant: water or methanol? (Hint: 1 L = 1000 cm3)
6. A 400.0 g glass coffee cup (C = 0.837 J/g°C) at room temperature, 20.°C, is plunged into hot dishwater at 80.°C. If the temperature of the cup reaches that of the dishwater, how much heat does the cup absorb?
7. Five kilograms of ice cubes are moved from the freezing compartment of a refrigerator into a home freezer. The refrigerator's freezing compartment maintains a temperature of -4.0°C. The home freezer is kept at -17°C. How much heat does the freezer's cooling system remove from the ice cubes?
8. A 250.0 kg cast iron car engine contains water as a coolant. Suppose the engine's temperature is 35.0°C when it is shut off. The air temperature is 10.0°C. The heat given off by the engine and the water in it as they cool to air temperature is 4400. kJ. What mass of water is used to cool the engine? You may assume that the temperature of the water and the temperature of the engine are always equal.
9. An 800.0 g block of unknown metal is heated in boiling water and then removed to a Styrofoam cup filled with room temperature water. The metal loses 8150 J of heat to the water as its temperature changes by 80.0°C. What is the specific heat and the identity of the metal?
1) 78.4 kJ / 2) 1400 J / 3) 1.02 x 10 6 J / 4) 10.0°C / 5) 21.5°C; water6) 20 kJ / 7) 133 kJ / 8) 15.2 kg / 9) 0.127 J/g°C; lead
B. Heat Transfer
1. Suppose the same amount of heat needed to raise the temperature of 50.0 g of water from 0°C to 100.°C is added to 50.0 g of zinc. What is the temperature change for the zinc?
2. A 200.0 g sample of water at 80.0°C is mixed with 200.0 g of water at 10.0°C in a Styrofoam cup. What is the final temperature of the water mixture?
3. A 600.0 g sample of water at 90.0°C is added to 400.0 g of water at room temperature (22.0°C). What is the final temperature of the mixture if no heat is lost to the surroundings?
4. A 400.0 g sample of ethyl alcohol at 16°C is mixed with 400.0 g of water at 85°C in a coffee cup calorimeter. What is the final temperature of the mixture?
5. A 100.0 g piece of copper heated to 90.0°C is placed in a Styrofoam cup containing 200.0 g of water at 20.0°C. What is the temperature when thermal equilibrium is achieved?
6. A 10.0 kg piece of zinc at 71.0°C is placed in an insulated container containing 20.0 kg of water at 10.0°C. What is the final temperature of the zinc?
7. A 100.0 g mass of an unknown metal at 100.0°C is transferred to a coffee cup calorimeter containing 100.0 g of water at 10.0°C. Thermal equilibrium is reached at 25.0°C. What is the specific heat of the metal?
8. A 100.0 g sample of an unknown metal at 100.0°C is placed in 200.0 g of water at 20.0°C. The final temperature of the mixture is 21.6°C. Determine the specific heat of tungsten.
9. What mass of water at room temperature (25.0°C) is required to cool a 200.0 g piece of lead from 85.0°C to 30.0°C?
Use the table below for questions 10-15.
Substance / Specific Heat(J/kg°C)
aluminum / 900
copper / 387
glass / 837
gold / 129
iron / 448
lead / 128
silver / 234
Note: For the following problems, neglect any heat transfer to or from the surroundings.
10. A 400.0 g iron horseshoe initially at 500.0°C is dropped into a bucket containing 20.0 kg of water at 22°C. What is the equilibrium temperature?
11. A 400.0 g sample of an unknown liquid at 80.0°C is poured into 400.0 g of water at 40.0°C. The final equilibrium temperature of the mixture is 49.0°C. What is the specific heat of the liquid?
12. What mass of water at 25°C must be allowed to reach thermal equilibrium with a 3.0 kg gold bar at 100°C in order to lower the temperature of the bar to 50°C?
13. A block of copper of mass 200.0 g at a temperature of 90.0°C is dropped into 400.0 g of water at 27°C. The water is contained in a 300.0 g glass container that remains in thermal equilibrium with the water. What is the final temperature of the mixture?
14. An aluminum cup contains 225 g of water at 27°C. A 400.0 g sample of silver at an initial temperature of 87°C is placed into the water. A 40.0 g copper stirrer initially sitting in the water is used to stir the mixture until it reaches it final equilibrium temperature of 32°C. Calculate the mass of the aluminum cup.
15. In a foundry operation, molten lead of mass 90.0 g at 327.3°C is poured into an iron casting block that has a mass of 300.0 g and initially at 20.0°C. What is the equilibrium temperature of the system?
1) 1080°C / 2) 45.0°C / 3) 62.8°C / 4) 59.6°C / 5) 23.1°C6) 12.7°C / 7) 0.836 J/g°C / 8) 0.171 J/g°C / 9) 68.4 g
10) 23°C / 11) 1215 J/kg°C / 12) 185 g
13) 29.4°C / 14) 81.8 g / 15) 56.5°C
C. Phase Changes
Water / MercuryHeat of fusion / 334 J/g / 11.5 J/g
Heat of vaporization / 2260 J/g / 272 J/g
1. How much heat must be absorbed to change 50.0 g of ice at 0°C to water at 0°C?
2. How much heat is released when 50.0 g of steam at 100°C is condensed to water at 100°C?
3. How much heat is absorbed by 100.0 g of ice at –20.0°C to become water at 0°C?
4. A 200.0 g sample of water at 60.0°C is heated to steam at 140.0°C. How much heat was absorbed?
5. How much heat is needed to change 300.0 g of ice at –30.0°C to steam at 130.0°C?
6. How much heat is removed from 60.0 g of steam at 100.0°C when it is changed to water at 20.0°C?
7. The specific heat of liquid mercury is 0.140 J/g°C. How much heat is needed to take 1.00 kg of mercury from 10.0°C to its boiling point (357°C) and completely vaporize the mercury?
8. Years ago, a block of ice with a mass of 20.0 kg was used daily in a home icebox. The temperature of the ice was 0°C when it was delivered. As it melted, how many joules of heat did a block this size absorb?
9. A 40.0 g sample of chloroform is condensed from vapor at 61.6°C to a liquid at 61.6°C. This condensation liberates 9870 joules of heat. What is the heat of vaporization of chloroform?
10. A 50.0 g sample of ice at 0°C is placed in a coffee-cup calorimeter containing 400.0 g of water at 50.0°C. What is the final temperature of the mixture?
1) 16.7 kJ / 2) 1.13 x 105 J / 3) 37.5 kJ / 4) 502 kJ / 5) 940 kJ6) 156 kJ / 7) 319 kJ / 8) 6680 kJ / 9) 247 J/g / 10) 35.6°C