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Thermo/Gas/Quantum Review

Thermo/Gas/Quantum Review. Calculate the internal energy, Δ 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.

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Thermo/Gas/Quantum Review

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  1. Thermo/Gas/QuantumReview

  2. Calculate the internal energy, ΔE, 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 Tro Chemistry: A Molecular Approach

  3. Calculate the internal energy, ΔE, 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 Tro Chemistry: A Molecular Approach

  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 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 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 Tro Chemistry: A Molecular Approach

  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 Tro Chemistry: A Molecular Approach

  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?2H2 (l)+ O2(l)→ 2 H2O (l)ΔHºrxn = –571.6 kJ • –571.6 • –285.8 • –1.87 x 1010 • –3.74 x 1010 • –7.55 x 107 Tro Chemistry: A Molecular Approach

  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?2H2 (l)+ O2(l)→ 2 H2O (l)ΔHºrxn = –571.6 kJ • –571.6 • –285.8 • –1.87 x 1010 • –3.74 x 1010 • – 7.55 x 107 Tro Chemistry: A Molecular Approach

  10. Ethanol is used as an additive in many fuels today. What is ΔHºrxn (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 Tro Chemistry: A Molecular Approach

  11. Ethanol is used as an additive in many fuels today. What is ΔHºrxn (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 Tro Chemistry: A Molecular Approach

  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 18.5°C. 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 1018Hz. • 7.1 x 10–11 • 7.1 x 10–2 • 1.3 x 1027 • 1.4 x 1010 • 7.1 x 10–18 Tro Chemistry: A Molecular Approach

  27. Determine the wavelength (in nm) of an X-ray with a frequency of 4.2 x 1018Hz. • 7.1 x 10–11 • 7.1 x 10–2 • 1.3 x 1027 • 1.4 x 1010 • 7.1 x 10–18 Tro Chemistry: A Molecular Approach

  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 10–38 • 4.81 x 10– 41 • 1.08 x 10– 34 • 1.08 x 10– 37 • 1.08 x 10– 40 Tro Chemistry: A Molecular Approach

  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 10–38 • 4.81 x 10– 41 • 1.08 x 10– 34 • 1.08 x 10– 37 • 1.08 x 10– 40 Tro Chemistry: A Molecular Approach

  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 Tro Chemistry: A Molecular Approach

  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 Tro Chemistry: A Molecular Approach

  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 Tro Chemistry: A Molecular Approach

  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 Tro Chemistry: A Molecular Approach

  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 Tro Chemistry: A Molecular Approach

  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 Tro Chemistry: A Molecular Approach

  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?

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