Thermo/Gas/Quantum Review

1
Thermo/Gas/QuantumReview
2
Calculate the internal energy, ?E, for a system
that does 422 J of work and loses 227 J of energy
as heat.

• 649 J
• 649 J
• 0 J
• 195 J
• 195 J

3
Calculate the internal energy, ?E, for a system
that does 422 J of work and loses 227 J of energy
as heat.

• 649 J
• 649 J
• 0 J
• 195 J
• 195 J

4
A 3.54 g piece of aluminum is heated to 96.2 ºC
and allowed to cool to room temperature, 22.5 ºC.
Calculate the heat (in kJ) associated with the
cooling process. The specific heat of aluminum
is 0.903 J/ g K

• 0.236
• 236
• 236
• 0.236
• 0.638

Tro Chemistry A Molecular Approach
5
A 3.54 g piece of aluminum is heated to 96.2 ºC
and allowed to cool to room temperature, 22.5 ºC.
Calculate the heat (in kJ) associated with the
cooling process. The specific heat of aluminum
is 0.903 J/ g K

• 0.236
• 236
• 236
• 0.236
• 0.638

Tro Chemistry A Molecular Approach
6
A 4.25 g sample of cyclohexane (C6H12) is
combusted in a bomb calorimeter with a total heat
capacity of 5.86 kJ/ ºC. The temperature of the
calorimeter increases from 23.5 ºC to 39.8 ºC.
What is the heat of combustion for cyclohexane in
kJ/ mol?

• 95.5
• 95.5
• 1890
• 1890
• 22.5

7
A 4.25 g sample of cyclohexane (C6H12) is
combusted in a bomb calorimeter with a total heat
capacity of 5.86 kJ/ ºC. The temperature of the
calorimeter increases from 23.5 ºC to 39.8 ºC.
What is the heat of combustion for cyclohexane in
kJ/ mol?

• 95.5
• 95.5
• 1890
• 1890
• 22.5

8
The main engines of the Space Shuttle burn
hydrogen to produce water. How much heat (in kJ)
is associated with this process if 1.32 x 105 kg
of liquid H2 is burned?2 H2 (l ) O2 (l ) ? 2
H2O (l ) ?Hºrxn 571.6 kJ

• 571.6
• 285.8
• 1.87 x 1010
• 3.74 x 1010
• 7.55 x 107

9
The main engines of the Space Shuttle burn
hydrogen to produce water. How much heat (in kJ)
is associated with this process if 1.32 x 105 kg
of liquid H2 is burned?2 H2 (l ) O2 (l ) ? 2
H2O (l ) ?Hºrxn 571.6 kJ

• 571.6
• 285.8
• 1.87 x 1010
• 3.74 x 1010
• 7.55 x 107

10
Ethanol is used as an additive in many fuels
today. What is ?Hºrxn (kJ) for the combustion of
ethanol.2 C2H5OH (l ) 6 O2 (g) ? 4 CO2 (g)
6 H2O (l )

• 401.7
• 401.7
• 2469
• 2734
• 2734

11
Ethanol is used as an additive in many fuels
today. What is ?Hºrxn (kJ) for the combustion of
ethanol.2 C2H5OH (l ) 6 O2 (g) ? 4 CO2 (g)
6 H2O (l )

• 401.7
• 401.7
• 2469
• 2734
• 2734

12

• If a 2.533 g sample of a metal was dissolved in
  50.0 g of a dilute HCl solution. The temperature
  of the calorimeter and its contents to rise from
  22.4oC to 61.2oC, calculate the heat of reaction
  per g for the metal. (The 50.0 g of acid
  solution has a specific heat of 4.168 J/g K, and
  the calorimeter has a heat capacity of 39.2J/K.)
•  The hydrogen gas from the experiment above was
  collected in a 452 mL at 30.0oC and 731 torr
  pressure, how many moles of hydrogen were
  collected?
•  What is the molar mass of the metal? (Previous
  experiments have shown the metal to form a
  chloride of the formula MCl3. Write a balanced
  chemical reaction and determine how many moles of
  the metal reacted.)
•  Calculate the molar heat of reaction of the
  metal.

13

• A piece of stainless steel (specific heat 0.50
  J/goC) is taken from an oven at 478oC and
  immersed in 55.0 g of water at 35.4 oC. 5.60
  grams of the water evaporate. What is the mass
  of the piece of stainless steel?

14

• You hold a gram of copper in one hand and a gram
  of aluminum in the other. Each metal was
  originally at 0oC. (Both metals are in the shape
  of a little ball that fits into your hand.) If
  they both take up heat at the same rate, which
  will warm to your body temperature first?
  Explain your reasoning.
• Specific heats
• Al 0.902 J/g K
• Cu 0.385 J/g K

15

• The sketch on the right shows two identical
  beakers with different volumes of water at the
  same temperature.
• Is the thermal energy content of beaker 1 greater
  than, less than, or equal to that of beaker 2?
  Explain your reasoning.
•  If the same quantity of thermal energy were
  transferred to each beaker, would the temperature
  of beaker 1 be greater than, less than, or equal
  to that of beaker 2? Explain your reasoning.

16

• Steam burns are very painful, mostly because of
  the heat transferred during condensation of the
  steam into liquid water.
• How much heat is transferred to the body if one
  gram of steam at 100 oC condenses and cools to
  body temperature (37 oC)?
• What percentage of this value is due to the
  condensation of steam?

17

• At the molecular level, how does hot water differ
  from cold water?

18

• Given the reaction
• 3Fe2O3(s) CO(g) ? 2Fe3O4(s) CO2(g) DH -46
  kJ
• Determine the DH for the following reactions
•  
• 2 Fe2O3(s) 2/3 CO(g) ? 4/3 Fe3O4(s) 2/3
  CO2(g)
•  
• 6 Fe3O4(s) 3 CO2(g) ? 9 Fe2O3(s) 3
  CO(g)
•  

19

• Given the following Diels Alder reaction
• Use bond energies to estimate the enthalpy of
  reaction. (Look for clever ways to get there.)

20

• A compound contains only C, H and N. It is
  58.51 C and 7.37 H by mass. Helium effuses
  through a porous frit 3.20 times as fast as the
  compound does. Determine the empirical and
  molecular formulas of this compound.

21

• At elevated temperatures, sodium chlorate
  decomposes to produce sodium chloride and oxygen
  gas. A 0.8765 g sample of impure sodium chlorate
  was heated until the production of oxygen ceased.
  The oxygen gas collected over water occupied
  57.2 mL at a temperature of 22 oC and a pressure
  of 734 torr. Calculate the mass percent of
  NaClO3 in the original sample. ( At 22oC the
  vapor pressure of water is 19.38 torr.)
• Hint - find
• Moles O2 collected
• Balanced Equation
• Mass NaClO3 decomposed
• Percent NaClO3

22

• A sample of dry ice (solid CO2) is placed into a
  sealed 5.0 L flask and allowed to undergo
  sublimation. Upon completion the pressure in the
  flask is measured to be 850.0 torr and the
  temperature is 18.5C. How many grams of dry ice
  were placed in the flask?

23

• An unknown gas has a density of 8.06 g/L at a
  pressure of 1.50 atm and 295K. Calculate the
  molar mass of the gas.

24

• A vacuum pump exhausts a heavy-walled 1.20-L
  round-bottomed flask to a pressure of 1.04 x
  10-6torr. How many particles are present if the
  temperature is 273 K?

25

• A particular balloon is designed by a
  manufacturer to be inflated to a volume of no
  more than 2.5 L. If the balloon is filled with
  2.0 L of helium, at sea level, is released, and
  rises to an altitude at which atmospheric
  pressure is only 500. mm Hg, will the balloon
  burst? Assume constant temperature. Demonstrate
  your reasoning.

26
Determine the wavelength (in nm) of an X-ray with
a frequency of 4.2 x 1018 Hz.

• 7.1 x 1011
• 7.1 x 102
• 1.3 x 1027
• 1.4 x 1010
• 7.1 x 1018

27
Determine the wavelength (in nm) of an X-ray with
a frequency of 4.2 x 1018 Hz.

• 7.1 x 1011
• 7.1 x 102
• 1.3 x 1027
• 1.4 x 1010
• 7.1 x 1018

28
A major league pitcher throws a 148.8 g baseball
at a speed of 92.5 mph (41.4 m/s). What is the
de Broglie wavelength of the baseball in meters?

• 4.81 x 1038
• 4.81 x 10 41
• 1.08 x 10 34
• 1.08 x 10 37
• 1.08 x 10 40

29
A major league pitcher throws a 148.8 g baseball
at a speed of 92.5 mph (41.4 m/s). What is the
de Broglie wavelength of the baseball in meters?

• 4.81 x 1038
• 4.81 x 10 41
• 1.08 x 10 34
• 1.08 x 10 37
• 1.08 x 10 40

30
An electron in a hydrogen atom in the n 6
energy level emits 109.4 kJ/ mol of energy in a
transition to a lower energy level. To what
energy level does the electron fall?

• 1
• 2
• 3
• 4
• 5

31
An electron in a hydrogen atom in the n 6
energy level emits 109.4 kJ/ mol of energy in a
transition to a lower energy level. To what
energy level does the electron fall?

• 1
• 2
• 3
• 4
• 5

32
Which of the following transitions for an
electron in a hydrogen atom would release the
largest quantum of energy?

• n 3 ? n 1
• n 4 ? n 3
• n 1 ? n 4
• n 2 ? n 1

33
Which of the following transitions for an
electron in a hydrogen atom would release the
largest quantum of energy?

• n 3 ? n 1
• n 4 ? n 3
• n 1 ? n 4
• n 2 ? n 1

34
Which of the following is NOT an allowed set of
quantum numbers?

• n 4 l 3 ml 3
• n 1 l 0 ml 0
• n 5 l 4 ml 2
• n 2 l 1 ml 0
• n 3 l 3 ml 2

35
Which of the following is NOT an allowed set of
quantum numbers?

• n 4 l 3 ml 3
• n 1 l 0 ml 0
• n 5 l 4 ml 2
• n 2 l 1 ml 0
• n 3 l 3 ml 2

36

• The ionization energy of phosphorous is 1012
  kJ/mol.
• What is the energy required to eject one electron
  from an atom of phosphorous?
•   
• What is the frequency of light required to just
  eject an electron from an atom of phosphorous?
•   
• What is the wavelength of this light?
•  
• What frequency of light would be required to
  eject an electron with a kinetic energy of 4.1 x
  10-19 J?

37

• How do the 2 p orbitals differ from one another?

38

• Scientists use emission spectra to confirm the
  presence of an element in materials of unknown
  composition. Why is this possible?

39

• Explain the process of emission of light by an
  atom. Use diagrams if useful.

40

• Consider two beams of the same yellow light.
  Imagine that one beam has its wavelength doubled
  the other has its frequency doubled. Which of
  these two beams is then in the ultraviolet
  region? Explain.

41

• Carbon absorbs energy at a wavelength of 150 nm.
  The total amount of energy emitted by a carbon
  sample is 1.98 x 105 J. Calculate the number of
  carbon atoms present in the sample, assuming that
  each atom emits one photon.

42
Which are permissible sets of quantum numbers for
an electron in a hydrogen atom?
43
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