Physical Science Institute
Summer 2013
States of Matter
Self-Assessment-Part 2
____1. In an accident some drums of uranium hexafluoride were lost in the English Channel, which is known for its cold
water (about 17oC). Given the freezing point of uranium hexafluoride is 64oC, in what physical state is the uranium
hexafluoride while in the cold water (17oC)?
A. solid
B. liquid
C. gas
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____2. A sample of water is placed in a sealed jar at 50 C. Over a few hours the volume of the water remains constant.
The water molecules that evaporate from the surface:
A. cause the remaining water to become warmer.
B. form bubbles of vapors that rise through the liquid.
C. are broken down into the elements oxygen and hydrogen.
D. return to the surface as frequently as others escape from the liquid.
____3. Differences in melting temperatures of different substances are explained by differences in
A. heat of fusion
C. chemical reactivity with oxygen
B. attractive forces between molecules and atoms.
D. density
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Physical Science Institute
Summer 2013
The circle in the diagram below represents a molecular view of water molecules in the liquid state:
LIQUID
= Oxygen
= Hydrogen
= H2O
____4. What would the magnified view show after all the water evaporates?
A
C
B
____5. At 50oC, the water molecules that evaporate from an open dish:
A. cause the remaining water to become warmer.
B. are broken down into the elements oxygen and hydrogen.
C. return to the surface as frequently as others escape from the liquid.
D. have more kinetic energy than those remaining in the liquid.
Questions 6 – 11 refer to the diagram below:
The graph below represents the temperature of a 10.0 gram sample of liquid bromine as it is cooled from 20oC to -20oC.
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Physical Science Institute
Summer 2013
Temp
o
( C)
20-
0-
-20-
t0
t1
t3
t2
t4
Time (sec)
____6. Which temperature on the graph represents the freezing point for this sample of bromine?
A. 20 oC
B. 0 oC
C. -7 oC
C. -20oC
D. no discernible freezing point from this data
____7. What is happening to the temperature of the bromine from t1 to t3 on the graph?
A. the temperature is increasing
B. the temperature is decreasing
C. the temperature remains the
same
____8. What time on the cooling graph for liquid bromine above represents where both solid and liquid phases exist at
the same temperature?
A. t0
B. t1
C. t2
D. t3
E. t4
____9. What happens to the average speed of the Br2 molecules from t1 to t3 on the graph?
A. The average speed increases
B. The average speed decreases
C. The average speed remains the same
____10. What happens to the average distance between the bromine molecules from t1 to t3 on the graph?
A. The average distance increases
B. The average distance decreases
C. The average distance remains the same
____11. What is the net heat transfer in the sample of bromine from t1 to t3 on the graph?
A. There is a net heat transfer from the bromine sample to the surroundings.
B. There is a net heat transfer from the surroundings to the bromine sample.
C. There is no net heat transfer between the bromine sample and the surroundings.
____12. Temperature measures average kinetic energy of the molecules,
A. heat is a measure of how densely packed the molecules of a substance are.
B. heat is a measure of the change in the total kinetic energy and total potential energy of the molecules.
C. heat is a measure of the change in the average kinetic energy and average potential energy between the
molecules.
D. heat & temperature measure the same properties of the molecules.
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Physical Science Institute
Summer 2013
____13. If the mass of bromine used in the investigation above had been 5.0 grams rather than 10.0 grams, which of the
following graphs would have resulted?
A.
Temp
o
( C)
20-
0-
-20-
t0
t1
t2
t3
t4
t3
t4
t3
t4
Time (sec)
B.
20-
Temp
o
( C)
0-
-20-
t0
t1
t2
Time (sec)
C.
Temp
o
( C)
20-
0-
-20-
t0
t1
t2
Time (sec)
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Physical Science Institute
Summer 2013
14. Two liquids at room temperature are contained in bottles that can dispense a drop at a time. “Bottle 1” contains
hexane and “Bottle 2” contains glycerin. One drop of each liquid is placed on a glass plate and it is observed that the
drop of hexane(Bottle 1) evaporates to dryness before the drop of glycerin (Bottle 2).
Using your knowledge of the kinetic molecular theory and intermolecular forces, explain the results of this activity.
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