KMT Chemistry Worksheet
Heat, Temperature, & Change of State
Name ________________ Period _____
Definition: calorie – the amount of energy required to raise the temperature of 1 gram of water by one degree Celsius
The diagram shows how temperature changes when
heat is added, beginning with ice several degrees
below zero.
1. Label on the diagram places where water is
solid
melting
liquid
boiling
gas
2. Locate the plateaus of the charted line.
Although heat is being added,
a) what is happening to the temperature?
b) Why is this?
3. The lower plateau shows where water is changing state from solid to liquid. This requires 80 calories per gram. This
amount of heat is called the Heat of Fusion (Hf) for water. Label the chart with this term and value.
4. The upper plateau shows where water is changing state from liquid to gas. This requires 540 calories per gram. This
amount of heat is called the Heat of Vaporization (Hv) for water. Label the chart with this term and value.
5. Determine the number of calories required to change 1 gram of water from:
a) 35oC to 45 oC __________ calories
d) -5 oC to 5 oC _____________ calories
b) 78oC to 90 oC __________ calories
e) 90oC to 104 oC __________ calories
c) -10oC to -8 oC __________ calories
f) -10oC to 110 oC __________ calories
6. Determine the number of calories required to change 200 grams of water from:
a) 35oC to 45 oC __________ calories
d) -5 oC to 5 oC _____________ calories
b) 78oC to 90 oC __________ calories
e) 90oC to 104 oC __________ calories
c) -10oC to -8 oC __________ calories
f) -10oC to 110 oC __________ calories
7. Compare the difference in heat that would be released to someone’s skin (assume skin is 35 oC) from 100 grams of
water that:
a) has just reached 100oC and is still liquid _______________ calories
b) has all turned to steam (gas) but is still 100 oC ______________ calories
Use the vapor pressure table to complete the chart for water’s boiling point as
it affects cooking and answer the questions that follow. Water is labeled “C”.
Ft. above sea
level
A
A
A
Pressure in
mm Hg
0
1000
2000
5000
7500
10,000
15,000
B
C
760
740
720
675
585
525
410
Boiling Point
o
Celsius
100oC
Cooking time
(minutes)
10
11
12
15
18
20
25
1. What are the boiling points of each of these substances at standard pressure (760 mm Hg)?
A ______________ B_________________ C _______________
2. What is the boiling point of liquid B at a pressure of 450 mm Hg? _____________
3. Suppose you wanted to boil water (C) at room temperature (20oC). To do this you would have to reduce the pressure
to at least _______________ mm Hg.
4. Suppose you wanted to boil liquid B at room temperature (20oC). You would have to reduce the pressure to at least
_________________ mm Hg.
5. At 400 mm Hg, liquid A has a boiling point of _____________oC.
CO2
B
E
1. On the water diagram, label the part of the graph that shows boiling point (bp) and freezing (melting) point (mp).
2. On one of the diagrams, label the point where all three states exist in equilibrium. This is the ________________.
3. What is the triple point pressure and temperature for carbon dioxide?
___________________________
4. At what point do only solids and liquids exist in equilibrium? ___________________
5. For water, what is the critical pressure (highest pressure that the substance could exist as a liquid)? ___________
6. For water, what is the critical temperature (highest temperature that the substance could exist as a liquid)? ___________
7. For carbon dioxide, what is the critical temperature? ___________ Which slope for freezing point do you think is
more typical of substances in general? The one for water or carbon dioxide? ____________ Why?