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Topic 1 – Matter and Energy
20. Heat calculations: Using heat of vaporization equation
1. How much heat is required to vaporize a 10 gram sample of water at its boiling point?
1) 2260 J 2) 3340 J 3) 22600 J 4) 33.4 J
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2. What is the total number of heat needed to vaporize a 25 g sample of water to steam at 100 C?
1) 83.5 KJ 2) 2.5 KJ 3) 90.4 KJ 4) 56.5 KJ
3. The heat of vaporization of a liquid substance is 670 J/g. How much heat must be added to a 40 g
sample of this liquid to change it to vapor at its boiling point?
1) 16.75 J 2) 26800 J 3) 1640 J 4) 670 J
4. How much heat must be removed from a 5 gram sample of steam to condense it to water at a
o Need Help? Study Book Pg 17 Set 27
constant temperature of 100 C?
1) 1657 J 2) 11300 J 3) 500 J 4) 2100 J
5. A 23 g sample of an unknown liquid substance absorbed 34 KJ of heat to change to gas at its
boiling point. What is the heat of vaporization of the unknown liquid?
1) 2.26 KJ/g 2) 782 KJ/g 3) 7.7 KJ/g 4) 1.5 KJ/g
21. Heat Calculations: Mixed heat problems
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1. What is the total number of kilojoules of heat needed to change 150 grams of ice to water at 0 C?
1) 50.1 2) 2.22 3) 184 4) 484
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2. How much heat is needed to change a 5.0 gram sample of water from 65 C to 75 C?
1) 210 J 2) 14 J 3) 21 J 4) 43 J
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3. When 200 grams of water is cooled from 50 C to 25 C, the total amount of heat energy released by
the water is
1) 34 J 2) 21 KJ 3) 42 KJ 4) 17 J
4. What amount of heat energy is needed to change a 20 g sample of water at 100 C to steam at the
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same temperature?
1) 905 KJ 2) 45.2 KJ 3) 1.13 KJ 4) .200 KJ
5. What is the total number of joules of heat energy released by a 2.5 gram sample of water to change Need Help? Study Book Pg 17 - 18 Set 27 - 28
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to ice at 0 C? 2) 8.4 J 3) 10.5 J 4) 835 J
1) 133 J
6. A 100 grams sample of water released 1672 Joules of heat to cool to a lower temperature. By how
much degree Celsius did, the water changed its temperature?
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1) 16.72 C 2) 1572 C 3) 4 C 4) 24 C
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7. A 12 g sample of water at 40 C absorbed 252 Joules of heat to change to a different temperature.
What would be the final temperature of the water?
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1) 5 C 2) 45 C 3) 35 C 4) 21 C
134 Copyright © 2010 E3 Scholastic Publishing. All Rights Reserved. Survivingchem.com
Topic 1 – Matter and Energy
20. Heat calculations: Using heat of vaporization equation
1. How much heat is required to vaporize a 10 gram sample of water at its boiling point?
1) 2260 J 2) 3340 J 3) 22600 J 4) 33.4 J
o
2. What is the total number of heat needed to vaporize a 25 g sample of water to steam at 100 C?
1) 83.5 KJ 2) 2.5 KJ 3) 90.4 KJ 4) 56.5 KJ
3. The heat of vaporization of a liquid substance is 670 J/g. How much heat must be added to a 40 g
sample of this liquid to change it to vapor at its boiling point?
1) 16.75 J 2) 26800 J 3) 1640 J 4) 670 J
4. How much heat must be removed from a 5 gram sample of steam to condense it to water at a
o Need Help? Study Book Pg 17 Set 27
constant temperature of 100 C?
1) 1657 J 2) 11300 J 3) 500 J 4) 2100 J
5. A 23 g sample of an unknown liquid substance absorbed 34 KJ of heat to change to gas at its
boiling point. What is the heat of vaporization of the unknown liquid?
1) 2.26 KJ/g 2) 782 KJ/g 3) 7.7 KJ/g 4) 1.5 KJ/g
21. Heat Calculations: Mixed heat problems
o
1. What is the total number of kilojoules of heat needed to change 150 grams of ice to water at 0 C?
1) 50.1 2) 2.22 3) 184 4) 484
o
o
2. How much heat is needed to change a 5.0 gram sample of water from 65 C to 75 C?
1) 210 J 2) 14 J 3) 21 J 4) 43 J
o o
3. When 200 grams of water is cooled from 50 C to 25 C, the total amount of heat energy released by
the water is
1) 34 J 2) 21 KJ 3) 42 KJ 4) 17 J
4. What amount of heat energy is needed to change a 20 g sample of water at 100 C to steam at the
o
same temperature?
1) 905 KJ 2) 45.2 KJ 3) 1.13 KJ 4) .200 KJ
5. What is the total number of joules of heat energy released by a 2.5 gram sample of water to change Need Help? Study Book Pg 17 - 18 Set 27 - 28
o
to ice at 0 C? 2) 8.4 J 3) 10.5 J 4) 835 J
1) 133 J
6. A 100 grams sample of water released 1672 Joules of heat to cool to a lower temperature. By how
much degree Celsius did, the water changed its temperature?
o
o
o
o
1) 16.72 C 2) 1572 C 3) 4 C 4) 24 C
o
7. A 12 g sample of water at 40 C absorbed 252 Joules of heat to change to a different temperature.
What would be the final temperature of the water?
o
o
o
o
1) 5 C 2) 45 C 3) 35 C 4) 21 C
134 Copyright © 2010 E3 Scholastic Publishing. All Rights Reserved. Survivingchem.com
