Energy of Phase Changes - AP Chemistry

1. What is the heat change when 1 mole of gas becomes a liquid?

   Molar heat of condensation. Energy released per mole when gas becomes liquid.

2. What is the phase change from gas to liquid called?

   Condensation. Phase transition from gaseous to liquid state.

3. What is the unit of molar heat of fusion in SI units?

   Joules per mole ($\text{J/mol}$). Standard unit expressing energy per mole for fusion.

4. What is the formula for calculating the heat required for a phase change?

   $q = m \times \text{ΔH}$. Where $q$ is heat, $m$ is mass, and $\text{ΔH}$ is enthalpy change.

5. What is the phase change from solid directly to gas called?

   Sublimation. Direct transition from solid to gas without liquid phase.

6. What does the symbol $m$ represent in the heat equations?

   Mass of the substance. Mass is a key variable in all heat transfer calculations.

7. What is the formula for calculating the heat required for a phase change?

   $q = m \times \text{ΔH}$. Where $q$ is heat, $m$ is mass, and $\text{ΔH}$ is enthalpy change.

8. What is the enthalpy change for the transition from liquid to solid?

   $-\text{ΔH}_{\text{fusion}}$. Freezing releases energy, opposite sign of fusion.

9. What is the heat change when 1 mole of gas becomes a liquid?

   Molar heat of condensation. Energy released per mole when gas becomes liquid.

10. What is the energy change for converting 1 mole of solid directly to gas?

    Molar heat of sublimation. Energy per mole for direct solid-to-gas transition.

11. What is the phase change from gas directly to solid called?

    Deposition. Direct phase transition from gas to solid state.

12. What does the symbol $c$ represent in the formula $q = m \times c \times \text{ΔT}$?

    Specific heat capacity. Energy required to raise temperature per unit mass per degree.

13. What is the energy change for converting 1 mole of solid directly to gas?

    Molar heat of sublimation. Energy per mole for direct solid-to-gas transition.

14. What is the term for the heat change when 1 mole of a liquid becomes a gas?

    Molar heat of vaporization. Energy change per mole for liquid-to-gas transition.

15. What is the energy change associated with the phase change of freezing?

    Latent heat of fusion. Freezing involves the same energy as fusion but opposite direction.

16. What is the term for the heat change when 1 mole of a solid becomes a liquid?

    Molar heat of fusion. Energy change per mole for solid-to-liquid transition.

17. What is the term for the heat required to convert 1 gram of a solid to a gas?

    Latent heat of sublimation. Energy for direct solid-to-gas transition per unit mass.

18. What is the term for the energy change when a liquid turns to gas without temperature change?

    Latent heat of vaporization. Energy change for liquid-to-gas transition at constant temperature.

19. Find the heat released by 60g of steam condensing, given $\text{ΔH}_{\text{vap}} = 2260 \text{J/g}$.

    135,600 J. $q = 60\text{g} \times 2260\text{J/g} = 135,600\text{J}$

20. What is the phase change from liquid to solid called?

    Freezing. Phase transition from liquid to solid state.

21. What is the unit of latent heat of fusion in the SI system?

    Joules per gram ($\text{J/g}$). Standard unit expressing energy per unit mass for fusion.

22. What does the symbol $q$ represent in the context of phase changes?

    Heat energy. Represents the thermal energy transferred during phase transitions.

23. What is the typical unit for specific heat capacity?

    Joules per gram per degree Celsius ($\text{J/g°C}$). Standard unit for energy per mass per temperature change.

24. Calculate the heat absorbed by 25g of ice melting, given $\text{ΔH}_{\text{fusion}} = 334 \text{J/g}$.

    8,350 J. $q = 25\text{g} \times 334\text{J/g} = 8,350\text{J}$

25. What is the unit of molar heat of fusion in SI units?

    Joules per mole ($\text{J/mol}$). Standard unit expressing energy per mole for fusion.

26. What is the energy change for converting 1 mole of solid directly to gas?

    Molar heat of sublimation. Energy per mole for direct solid-to-gas transition.

27. Find the heat released by 60g of steam condensing, given $\text{ΔH}_{\text{vap}} = 2260 \text{J/g}$.

    135,600 J. $q = 60\text{g} \times 2260\text{J/g} = 135,600\text{J}$

28. What is the phase change from solid to liquid called?

    Melting. Phase transition from solid to liquid state.

29. What is the formula for calculating heat when temperature changes?

    $q = m \times c \times \text{ΔT}$. Used for heating or cooling without phase change.

30. State the formula for calculating heat during a temperature change.

    $q = m \times c \times \text{ΔT}$. Where $c$ is specific heat capacity and $\text{ΔT}$ is temperature change.

31. What does the symbol $q$ represent in the context of phase changes?

    Heat energy. Represents the thermal energy transferred during phase transitions.

32. What phase change is associated with the latent heat of fusion?

    Solid to liquid. Fusion refers to the melting process from solid to liquid.

33. What does the symbol $q$ represent in the context of phase changes?

    Heat energy. Represents the thermal energy transferred during phase transitions.

34. Determine the heat change for vaporization of 30g of water, given $\text{ΔH}_{\text{vap}} = 2260 \text{J/g}$.

    67,800 J. $q = 30\text{g} \times 2260\text{J/g} = 67,800\text{J}$

35. Identify the phase change for the latent heat of vaporization.

    Liquid to gas. Vaporization specifically describes the liquid-to-gas transition.

36. What is the formula for calculating heat when temperature changes?

    $q = m \times c \times \text{ΔT}$. Used for heating or cooling without phase change.

37. What happens to the temperature of a substance during a phase change at constant pressure?

    Remains constant. Energy goes into breaking bonds, not changing temperature.

38. Determine the heat change when a 20g ice cube melts, given $\text{ΔH}_{\text{fusion}} = 334 \text{J/g}$.

    6,680 J. $q = 20\text{g} \times 334\text{J/g} = 6,680\text{J}$

39. What is the energy change associated with the phase change of freezing?

    Latent heat of fusion. Freezing involves the same energy as fusion but opposite direction.

40. Calculate the energy required to freeze 15g of water, given $\text{ΔH}_{\text{fusion}} = 334 \text{J/g}$.

    5,010 J. $q = 15\text{g} \times 334\text{J/g} = 5,010\text{J}$

41. What is the phase change from solid directly to gas called?

    Sublimation. Direct transition from solid to gas without liquid phase.

42. What does the symbol $m$ represent in the heat equations?

    Mass of the substance. Mass is a key variable in all heat transfer calculations.

43. What is the phase change from solid directly to gas called?

    Sublimation. Direct transition from solid to gas without liquid phase.

44. What is the phase change from solid to liquid called?

    Melting. Phase transition from solid to liquid state.

45. Calculate the heat required to vaporize 100g of water, given $\text{ΔH}_{\text{vap}} = 2260 \text{J/g}$.

    226,000 J. $q = 100\text{g} \times 2260\text{J/g} = 226,000\text{J}$

46. What is the term for the energy change when a liquid turns to gas without temperature change?

    Latent heat of vaporization. Energy change for liquid-to-gas transition at constant temperature.

47. What does the symbol $\text{ΔH}$ represent in phase change calculations?

    Enthalpy change. Represents the energy change per unit mass during phase transitions.

48. What happens to the temperature of a substance during a phase change at constant pressure?

    Remains constant. Energy goes into breaking bonds, not changing temperature.

49. What is the phase change from gas directly to solid called?

    Deposition. Direct phase transition from gas to solid state.

50. What is the term for the heat change when 1 mole of a solid becomes a liquid?

    Molar heat of fusion. Energy change per mole for solid-to-liquid transition.

51. Calculate the heat required to vaporize 100g of water, given $\text{ΔH}_{\text{vap}} = 2260 \text{J/g}$.

    226,000 J. $q = 100\text{g} \times 2260\text{J/g} = 226,000\text{J}$

52. State the formula for calculating heat during a temperature change.

    $q = m \times c \times \text{ΔT}$. Where $c$ is specific heat capacity and $\text{ΔT}$ is temperature change.

53. What is the term for the heat change when 1 mole of a solid becomes a liquid?

    Molar heat of fusion. Energy change per mole for solid-to-liquid transition.

54. What is the typical unit for specific heat capacity?

    Joules per gram per degree Celsius ($\text{J/g°C}$). Standard unit for energy per mass per temperature change.

55. What is the energy change associated with the phase change of freezing?

    Latent heat of fusion. Freezing involves the same energy as fusion but opposite direction.

56. Calculate the energy required to freeze 15g of water, given $\text{ΔH}_{\text{fusion}} = 334 \text{J/g}$.

    5,010 J. $q = 15\text{g} \times 334\text{J/g} = 5,010\text{J}$

57. What is the energy change associated with the phase change of deposition?

    Latent heat of deposition. Energy released when gas transitions directly to solid.

58. What does the symbol $c$ represent in the formula $q = m \times c \times \text{ΔT}$?

    Specific heat capacity. Energy required to raise temperature per unit mass per degree.

59. What is the term for the heat change when 1 mole of a liquid becomes a gas?

    Molar heat of vaporization. Energy change per mole for liquid-to-gas transition.

60. What is the phase change from liquid to solid called?

    Freezing. Phase transition from liquid to solid state.

61. Identify the phase change for the latent heat of vaporization.

    Liquid to gas. Vaporization specifically describes the liquid-to-gas transition.

62. Calculate the heat released when 50g of steam condenses, given $\text{ΔH}_{\text{vap}} = 2260 \text{J/g}$.

    113,000 J. $q = 50\text{g} \times 2260\text{J/g} = 113,000\text{J}$

63. What is the phase change called when a gas turns into a solid?

    Deposition. Direct phase transition from gas to solid state.

64. Identify the phase change for the latent heat of vaporization.

    Liquid to gas. Vaporization specifically describes the liquid-to-gas transition.

65. Calculate the heat required to melt 50g of ice, given $\text{ΔH}_{\text{fusion}} = 334 \text{J/g}$.

    16,700 J. $q = 50\text{g} \times 334\text{J/g} = 16,700\text{J}$

66. What is the term for the heat required to change 1 gram of a substance from solid to liquid?

    Latent heat of fusion. Specific energy required for the melting process per gram.

67. What is the term for the heat required to convert 1 gram of a solid to a gas?

    Latent heat of sublimation. Energy for direct solid-to-gas transition per unit mass.

68. What does the symbol $\text{ΔH}$ represent in phase change calculations?

    Enthalpy change. Represents the energy change per unit mass during phase transitions.

69. What is the phase change from gas to liquid called?

    Condensation. Phase transition from gaseous to liquid state.

70. What is the term for the energy change when a liquid turns to gas without temperature change?

    Latent heat of vaporization. Energy change for liquid-to-gas transition at constant temperature.

71. What is the term for the heat required to convert 1 gram of a solid to a gas?

    Latent heat of sublimation. Energy for direct solid-to-gas transition per unit mass.

72. Calculate the energy required to freeze 15g of water, given $\text{ΔH}_{\text{fusion}} = 334 \text{J/g}$.

    5,010 J. $q = 15\text{g} \times 334\text{J/g} = 5,010\text{J}$

73. Calculate the heat required to vaporize 100g of water, given $\text{ΔH}_{\text{vap}} = 2260 \text{J/g}$.

    226,000 J. $q = 100\text{g} \times 2260\text{J/g} = 226,000\text{J}$

74. What does the symbol $c$ represent in the formula $q = m \times c \times \text{ΔT}$?

    Specific heat capacity. Energy required to raise temperature per unit mass per degree.

75. What is the phase change from liquid to solid called?

    Freezing. Phase transition from liquid to solid state.

76. What is the heat change when 1 mole of gas becomes a liquid?

    Molar heat of condensation. Energy released per mole when gas becomes liquid.

77. What is the unit of molar heat of fusion in SI units?

    Joules per mole ($\text{J/mol}$). Standard unit expressing energy per mole for fusion.

78. What is the enthalpy change for the transition from liquid to solid?

    $-\text{ΔH}_{\text{fusion}}$. Freezing releases energy, opposite sign of fusion.

79. Calculate the heat required to melt 50g of ice, given $\text{ΔH}_{\text{fusion}} = 334 \text{J/g}$.

    16,700 J. $q = 50\text{g} \times 334\text{J/g} = 16,700\text{J}$

80. What is the formula for calculating the heat required for a phase change?

    $q = m \times \text{ΔH}$. Where $q$ is heat, $m$ is mass, and $\text{ΔH}$ is enthalpy change.

81. What is the energy change associated with the phase change of deposition?

    Latent heat of deposition. Energy released when gas transitions directly to solid.

82. What is the term for the heat required to change 1 gram of a substance from solid to liquid?

    Latent heat of fusion. Specific energy required for the melting process per gram.

83. What is the phase change from gas directly to solid called?

    Deposition. Direct phase transition from gas to solid state.

84. What is the term for the heat required to change 1 gram of a substance from solid to liquid?

    Latent heat of fusion. Specific energy required for the melting process per gram.

85. What is the phase change from gas to liquid called?

    Condensation. Phase transition from gaseous to liquid state.

86. What happens to the temperature of a substance during a phase change at constant pressure?

    Remains constant. Energy goes into breaking bonds, not changing temperature.

87. What phase change is associated with the latent heat of fusion?

    Solid to liquid. Fusion refers to the melting process from solid to liquid.

88. What is the enthalpy change when 1 mole of water condenses?

    $-\text{ΔH}_{\text{vap}}$. Condensation releases energy, opposite sign of vaporization.

89. What is the enthalpy change for the transition from liquid to solid?

    $-\text{ΔH}_{\text{fusion}}$. Freezing releases energy, opposite sign of fusion.

90. What is the energy required to convert 10g of ice at 0°C to water at 0°C?

    3,340 J. $q = 10\text{g} \times 334\text{J/g} = 3,340\text{J}$

91. Calculate the heat absorbed by 25g of ice melting, given $\text{ΔH}_{\text{fusion}} = 334 \text{J/g}$.

    8,350 J. $q = 25\text{g} \times 334\text{J/g} = 8,350\text{J}$

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