Name: ___________________________________ Block: _______________ Date: ___________________
Unit 10 Practice Test
Objective 10.1: Interpret heating and cooling curves and phase diagrams.
Directions: Use the cooling curve below to answer the following questions:
100
A
80
B
C
60
Temperature (oC)
40
20
0
-20
-40
-60
-80
D
E
-100
F
-120
0
2
4
6
8
10
12
14
16
Time (min.)
1. State the boiling point of the substance in Celsius:
_________
2.
_________
Which segment represents the liquid being cooled?
3. Which segment represents freezing?
_________
4. How many minutes does it take from the time the substance begins to condense until it is completely liquid? ____
5. Use your Chemistry Reference Tables to identify this substance: ____________________
Directions: Base your answers to the following questions on the phase diagram of substance Y below.
6. In what state is compound Y at 300 K and 150
atm? _________________
7. What is the critical point of compound Y?
___________
__________
8. What phase change does Y undergo if a sample at
100 K and 100 atm is heated to 250 K?
________________________________
9. The phase change in #7 is
(exothermic/endothermic).
10. What is the boiling point of compound Y at 150
atm? _______________
Score box
A= 10/10 (100)
B= 9/10 (90)
NY
Objective 10.2: Calculate the heat lost or gained in temperature changes and phase changes.
Directions: Solve the following problems, including the correct FORMULA, WORK, UNITS, and SIG FIGS. Place
a BOX around your final answer.
1. During a chemical reaction, the temperature of 9.07 g of liquid water goes from 21.2°C to 16.5oC. Calculate q. [2]
2. How much heat is needed to melt 0.56 grams of ice at 0oC? [2]
3. What is the specific heat of a metal if 205.4 grams of it increases in temperature from 10.0oC to 30.0oC from the
addition of 575 J of heat energy.[2]
4. Identify the metal in question #3: ________________________________[1]
5. While planting a tree in his backyard, Pete uncovers a large nugget of gold! If it takes 1.5 kJ of heat to change its
temperature from 11°C to 96ºC, what is the mass of his gold nugget?[2]
The following questions involve the use of your Reference Tables.
6. A student adds 300 Joules of heat to two metal cubes of the same mass, which are both at 25oC. One cube is made
of nickel, while the other is made of zinc. Both cubes receive the exact same amount of heat. Which of the
following is true after the cubes absorb heat?
A.
B.
C.
D.
The nickel cube will have a higher final temperature than the zinc cube.
The zinc cube will have a higher final temperature than the nickel cube.
Both cubes will have the same final temperature.
There is not enough information to tell.
7. Discuss your rationale for your answer to question #6.
Score box
A= 10/10 (100)
B= 9/10 (90)
NY
Objective 3: Interpret a potential energy diagram. (p. 498-500)
( kJ )
Directions: The diagram below is a potential energy diagram for the overall reaction: H2 + Cl2  2HCl
2HCl
H2+ Cl2
1. Give the following values in kilojoules (kJ):
a)
Activation energy, Ea (forward reaction)
_________________
b) Heat of reaction (∆H)
_________________
c)
_________________
Potential energy of the products
d) Potential energy of the activated complex
_________________
2. Determine whether the following statements about the reaction 2HCl  H2 + Cl2 are TRUE (T) or FALSE (F)
based on the PE diagram above.
a)
b)
c)
d)
The reaction is endothermic.
The product molecules are less stable than the reactant molecules.
PEproducts > PEreactants
The bonds in the reactant molecules are stronger than the bonds in the product molecules.
3. A student adds 5.0 grams of a salt to a 100 mL of water at 22oC and
monitors the temperature of the water as he dissolves it in the water.
His data is shown below:
Time (s)
Temperature
(oC)
0
30
60
90
120
22.0
28.2
30.3
31.1
31.2
Discuss whether the dissolving of this salt is an endothermic or
exothermic process. [2]
Score box
A= 10/10 (100)
B=9/10 (90)
NY