GHS Honors Chemistry
Heat & Change of Phase Problems
Name: __________________________________ Date: __________ Block: _________
A. Heat Problems:
1.
A 50.0 gram piece of lead absorbs 400.0 Joules of heat and experiences a change in
temperature of 40.0oC. Calculate the specific heat of lead.
2.
A mass of water loses 40, 000 Joules of heat energy. If the change in temperature is
20.0oC, determine the mass of water.
3.
The temperature of a piece of zinc with a mass of 45.0 grams changes from 25.0oC to
60.0oC when the metal absorbs 850.0 Joules of heat. Determine the specific heat of
zinc.
4.
Find the number of grams of ice, at 0.0oC that could be melted by the addition of 3.6
kilojoules of heat.
B. Changes of Phase Problems: For each of the following, draw a sketch, and solve the
problem.
5.
Determine the amount of heat needed to raise the temperature of 20.0 grams of ice
at 0.0oC to water at 80.0oC.
6.
Find the heat lost by 20.0 grams of water at 40.0oC to form ice at - 20.0oC.
7.
How much heat energy is needed to raise the temperature of 50.0 grams of ice at 10.0oC to form steam at 120.0oC?
8.
Calculate the amount of heat lost by 120.0 grams of steam at 150.0oC to form ice at
-15.0oC.
9.
Determine the amount of heat that must be removed from 200.0 grams of steam at
100.0oC to become water at 20.0oC.
10. How much heat is required to raise the temperature of 30.0 g of H2O at -80.0oC to
150oC (Don’t forget the phase changes!).
11. Xylene has the following constants: M.P. = 25oC, B.P. = 80oC, Hf = 120 cal/g, Hv = 360
cal/g, Specific Heat(solid) = 0.25 cal/goC, Specific Heat(liq) = 0.30 cal/goC, Specific
Heat(gas) = 0.20 cal/goC. How much heat is given off when 40.0 grams of xylene has its
temperature dropped from 100.0oC, to 0.00oC?
12. Using the information above for xylene, what would the final temperature be if 10,200
calories were added to a 20.0 g sample originally at 15oC?
13. 230 calories are added to 92 g of liquid nitrogen and the temperature increases from 247oC to -182oC, without a phase change. What is the specific heat of liquid nitrogen?
GHS Honors Chemistry
Heat & Change of Phase Problems
Name: __________________________________ Date: __________ Block: _________
Answers:
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0.20 J/goC
478.5 grams
0.540 J/goC
10.8 grams
3200 calories
2600 calories
36750 calories
90300 calories
124000 calories
23600 calories
20 kcal
135oC
0.0385 cal/goC