6.4 Energy of Phase Changes

    Cards (36)

    • Exothermic phase changes release energy.

      True
    • What overcomes intermolecular forces during phase changes?
      Energy
    • What is the enthalpy of fusion for water (H2O)?
      6.01 kJ/mol
    • Order the phase changes by the type of energy required or released:
      1️⃣ Melting (requires energy)
      2️⃣ Boiling (requires energy)
      3️⃣ Freezing (releases energy)
      4️⃣ Condensation (releases energy)
      5️⃣ Sublimation (requires energy)
    • The enthalpy of fusion represents the energy required to change a substance from solid to liquid
    • The enthalpy of fusion is typically expressed in units of kJ/mol or kcal/mol
    • Phase changes occur when a substance absorbs or releases energy.

      True
    • What is the enthalpy of fusion for water (H2O)?
      6.01 kJ/mol
    • Match the phase change with its energy requirement:
      Melting ↔️ Requires energy (endothermic)
      Freezing ↔️ Releases energy (exothermic)
    • Condensation is an exothermic process.
      True
    • Common phase changes include melting, boiling, freezing, condensation, and sublimation
    • The enthalpy of fusion is generally lower than the enthalpy of vaporization
    • Phase changes can be either endothermic or exothermic
    • The enthalpy of fusion for water is 6.01 kJ/mol, while the enthalpy of vaporization is 40.7 kJ/mol
    • The melting of ice is an endothermic process because it absorbs energy
    • Steps to calculate energy changes during phase transitions:
      1️⃣ Identify the phase change
      2️⃣ Multiply the moles by the enthalpy value
      3️⃣ Determine if energy is required or released
    • The enthalpy of vaporization for water is higher than its enthalpy of fusion.
      True
    • What must energy overcome during phase changes to allow transitions between solid, liquid, and gas states?
      Intermolecular forces
    • Which phase change involves a substance directly transitioning from solid to gas?
      Sublimation
    • The enthalpy of fusion is expressed in kJ/mol.

      True
    • The enthalpy of vaporization for water (H2O) is 40.7 kJ/mol.

      True
    • Endothermic phase changes absorb energy.

      True
    • Calculating energy changes during phase changes requires multiplying the moles of substance by the corresponding enthalpy value.
      True
    • In freezer operation, what type of energy change occurs during water freezing?
      Exothermic
    • What do phase changes refer to?
      Transitions between states of matter
    • Phase changes occur when the energy of the system is increased or decreased
    • Adding heat energy to a solid can cause it to melt.

      True
    • Match the enthalpy type with its description:
      Enthalpy of fusion ↔️ Energy to change solid to liquid
      Enthalpy of vaporization ↔️ Energy to change liquid to gas
    • The enthalpy of fusion measures the energy required to change a substance from solid to liquid
    • What is the enthalpy of vaporization for water (H2O)?
      40.7 kJ/mol
    • The phase change from solid to liquid is called melting
    • What is the enthalpy of fusion for water (H2O) in kJ/mol?
      6.01
    • What does the enthalpy of vaporization depend on primarily?
      Intermolecular forces
    • Which phase change is an example of an endothermic process?
      Melting
    • What is the energy required to melt 2.5 mol of ice at 0°C using the enthalpy of fusion for water?
      15.025 kJ
    • To melt 3 moles of ice, 18.03 kJ of energy is required.

      True
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