Download AP CHEMISTRY CHAPTER 7 PROBLEM SET #2

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AP CHEMISTRY
CHAPTER 7
PROBLEM SET #2
(Questions 1-3) Write the letter of the phrase that answers the question or best completes
the statement on the line.
_____ 1.
1-propanol, CH3CH2CH2CH2OH, boils at 97oC and ethyl methyl ether,
CH3CH2OCH3, boils at 7oC, although each compound has an identical
chemical composition. The difference that is responsible for the higher
boiling temperature is
A.
molar mass.
B.
hydrogen bonding.
C.
density.
D.
specific heat.
E.
enthalpy.
_____ 2.
The Clausius-Clapeyron equation indicates that
I.
the greater the vapor pressure, the higher the entropy of the
vaporization.
II.
the higher the heat of vaporization, the steeper the slope of lnP vs
1/T.
III.
the enthalpy of vaporization is equal to the slope of the vapor
pressure vs. temperature.
A. I only
B. II only
_____ 3.
Which of the following would exist between atoms that had a large
difference in electronegativities?
A.
covalent bonding
B.
London dispersion forces
C.
hydrogen bonding
D.
ionic bonding
4.
C. III only
D.
I and II only
E. I, II and III
Based upon the following data, determine the ∆Hvap for magnesium and lithium.
In which metal is the bonding stronger?
Vapor Pressure
Temperature (°C)
(mm Hg)
Li
Mg
1.
750.
620.
10.
890.
740.
100.
1080.
900.
400.
1240.
1040.
760.
1310.
1110.
5.
The temperature inside a pressure cooker is 115°C.
a.
Calculate the vapor pressure inside the pressure inside the pressure cooker.
At 100.°C, the vapor pressure of water is 1.00 atm. For water, ∆Hvap is
40.7 kJ/mol.
b.
What would be the temperature inside the pressure cooker if the vapor
pressure of water was 3.50 atm? (At 100.°C, the vapor pressure of water is
1.00 atm. For water, ∆Hvap is 40.7 kJ/mol).
6.
What pressure would have to be applied to steam at 350.°C to condense the steam
to liquid water?
7.
The enthalpy of vaporization of acetone is 32.0 kJ/mol. The normal boiling point
of acetone is 56.5°C. What is the vapor pressure of acetone at 25.0°C?
8.
The complete structural formula of propane, C3H8, and methanoic acid, HCOOH,
are shown above.
a.
In the table below, write the type(s) of intermolecular attractive force(s)
that occur in each substance.
Substance
Propane
Methanoic acid
b.
9.
Boiling Point
229 K
374 K
Intermolecular Attractive Force(s)
Use principles of intermolecular attractive forces to explain why
methanoic acid has a higher boiling point than propane.
The vapor pressure of water at 25oC is 23.8 torr; ∆Hvap = 43.9 kJ/mol.
a.
Determine the vapor pressure of water at 70.oC.
b.
Determine the percentage error if your experimental results for vapor
pressure at 70oC give a result of 225 torr.
c.
10.
Give structural reasons that support the fact that the boiling temperature of
C2H5OH is 78oC and water is 100oC, (both at 760 torr).
The following table gives the vapor pressure of hexafluorobenzene as a function
of temperature.
Temperature (°C)
7.0
27.0
47.0
57.0
67.0
11.
Vapor pressure (torr)
32.41
92.47
225.1
334.4
482.9
a.
Determine the value of ∆Hvap.
b.
Use this data to determine the boiling point of the compound.
1-proponal, CH3CH2CH2OH, boils at 97oC and ethyl methyl ether, CH3CH2OCH3
boils at 7oC, although each compound has an identical chemical composition.
Explain why 1-propanol has a boiling point so much higher than ethyl methyl
ether.
12.
Rationalize the difference in boiling points for each of the following pairs of
substances:
a.
n-pentane
CH3CH2CH2CH2CH3
36.2oC
CH3
neopentane
H3C-C-CH3
9.5oC
CH3
13.
b.
n-Pentane
n-Propane
c.
n-Propane
dimethyl ether
CH3CH2CH2CH2CH3
CH3CH2CH3
CH3CH2CH3
CH3OCH3
36.2oC
-42oC
-42oC
-25oC
Predict which of the following substances would have a higher boiling point: Cl2
or I2. JUSTIFY YOUR ANSWER.