Thermal Energetics: Specific Heat & Latent Heat
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Questions and Answers

What is the temperature at which a solid turns into a liquid called?

  • Boiling point
  • Condensation point
  • Melting point (correct)
  • Freezing point

    • What does the law of conservation of energy state?

  • Energy can only be transformed from one form to another (correct)
  • Energy can be created and destroyed
  • Energy can increase without limit
  • Energy is always lost during transformations

    • Which phase change occurs at the boiling point?

  • Liquid to gas (correct)
  • Solid to gas
  • Solid to liquid
  • Gas to liquid

    • The amount of energy required to change a liquid to gas without changing its temperature is known as?

    <p>Latent Heat of Vaporization</p> Signup and view all the answers

    What is the SI unit for specific heat capacity?

    <p>J.kg-1 K-1</p> Signup and view all the answers

    When a material is heated without a change of state, the temperature will typically:

    <p>Increase</p> Signup and view all the answers

    What is the freezing point of a pure substance often associated with?

    <p>Melting point</p> Signup and view all the answers

    Which of these represents a phase change from gas to liquid?

    <p>Condensation</p> Signup and view all the answers

    How much steam at 100°C is needed to completely melt 3.2 kg of ice at 0°C?

    <p>0.47 kg</p> Signup and view all the answers

    How does the latent heat of vaporization compare to the latent heat of fusion?

    <p>Greater than</p> Signup and view all the answers

    How much water at 100°C can be converted to steam using 678 kJ of energy?

    <p>2.05 kg</p> Signup and view all the answers

    What is the final temperature of a 5 kg block of copper after receiving 46.2 kJ of energy?

    <p>44 °C</p> Signup and view all the answers

    How many joules are needed to change 10 grams of ice at -15 °C to water at 20 °C?

    <p>4483 J</p> Signup and view all the answers

    What is the specific heat capacity of water used in the calculations?

    <p>4190 J/kg °C</p> Signup and view all the answers

    What is the latent heat of fusion for ice?

    <p>3.33 x 10^5 J/kg</p> Signup and view all the answers

    What is the amount of energy required to raise the temperature of 1 kg of ice from -15 °C to 0 °C?

    <p>2100 J</p> Signup and view all the answers

    How much energy is required to melt 100 g of ice?

    <p>33.3 KJ</p> Signup and view all the answers

    What is the time required to convert all the ice into water at 0°C using a constant power of 1000 W?

    <p>56.235 sec</p> Signup and view all the answers

    What is the mass of steam at 100°C needed to completely melt all the ice?

    <p>22.19 g</p> Signup and view all the answers

    What would be the final state of the ice if it received 450 KJ of heat?

    <p>Water and steam</p> Signup and view all the answers

    In the given exercise, what is the final temperature of the mixture when 540 g of ice at 0°C is mixed with 540 g of water at 80°C?

    <p>40°C</p> Signup and view all the answers

    What is the value of the latent heat of fusion for ice as given in the content?

    <p>3.33 x 10^5 J/kg</p> Signup and view all the answers

    What is the specific heat capacity of water as mentioned in the content?

    <p>4190 J/kg°C</p> Signup and view all the answers

    What energy is given off when steam condenses to water at 100°C?

    <p>2.26 x 10^6 J/kg</p> Signup and view all the answers

    What is the formula for calculating the amount of heat energy when a substance changes temperature?

    <p>Q = m c ΔT</p> Signup and view all the answers

    Which of the following represents the specific heat capacity for wood?

    <p>1700 J/kg°C</p> Signup and view all the answers

    What does the latent heat of fusion (Lf) refer to?

    <p>Heat required to melt a solid into a liquid</p> Signup and view all the answers

    At which point does the latent heat of vaporization (Lv) occur?

    <p>At the boiling point</p> Signup and view all the answers

    Which substance has the highest specific heat capacity listed?

    <p>Water</p> Signup and view all the answers

    How is the heat energy during phase changes described mathematically?

    <p>Q = m L</p> Signup and view all the answers

    What happens to the temperature of a substance during a phase change?

    <p>It remains constant.</p> Signup and view all the answers

    Which of the following is true about substances with high specific heat capacity?

    <p>They require more energy to change temperature.</p> Signup and view all the answers

    What is the specific heat capacity of mercury?

    <p>140 J/kg°C</p> Signup and view all the answers

    Which process would involve the latent heat of fusion?

    <p>Melting ice into water</p> Signup and view all the answers

    What does 'Q (lost) = Q (gained)' represent?

    <p>Conservation of energy during phase changes</p> Signup and view all the answers

    Which statement about latent heat and temperature at phase changes is true?

    <p>Both latent heat of fusion and vaporization occur at constant temperature.</p> Signup and view all the answers

    At what temperature does absolute zero occur?

    <p>-273.15°C</p> Signup and view all the answers

    Study Notes

    Quantity of Heat

    • Heat energy (Q) is calculated differently depending on whether a phase change occurs or not.

    • Q = mcΔT (for one phase, solid, liquid, or gas)

    • m = mass

    • c = specific heat capacity

    • ΔT = change in temperature

    • Q = mL (for phase changes)

    • m = mass

    • L = latent heat (heat of fusion or vaporization)

    Specific Heat (c) & Latent Heat (L)

    • Specific heat (c) is the amount of heat energy required to raise the temperature of a unit of mass of a substance by 1° temperature.
    • Substances with higher specific heat capacity take longer to warm or cool.
    • Latent heat (L) is the amount of heat energy required to change the phase of a unit of mass.
    • Latent heat of fusion (Lf) is the energy required to change a substance from solid to liquid.
    • Latent heat of vaporization (Lv) is the energy required to change a substance from liquid to gas.

    Specific Heat Values for Various Substances (c)

    • A table listing various substances and their respective specific heat capacities (in J/kg.°C).

    Phase Change

    • Phase changes involve melting, freezing, vaporization, and condensation.
    • Lf (latent heat of fusion) = Lf (latent heat of freezing)
    • Lv (latent heat of vaporization) = latent heat of condensation

    Latent Heat of Fusion and Vaporization for Various Substances

    • A table showing the melting points, latent heat of fusion, boiling points, and latent heat of vaporization for various substances.

    Heating Curve of Water

    • Water's heating curve illustrates how temperature changes with added heat concerning phase changes.
    • Q = mcΔT (no phase change)
    • Q = mL (phase change)

    Calculations

    • Examples of calculations showing how to determine energy (heat) needed for various phase change processes, including calculations related to changing from one phase to another, and taking into consideration different substances.

    Important Definitions

    • Absolute zero (0 K): The point when molecular movement stops.
    • Melting point: Temperature at which solid turns to liquid
    • Freezing point: Temperature at which liquid turns to solid
    • Boiling point: Temperature at which liquid turns to gas.
    • Condensation point: Temperature at which gas turns to liquid.
    • Law of Conservation of Energy: Energy can neither be created nor destroyed, only transformed from one form to another. The energy lost by a hotter object is gained by a cooler object.

    Multiple Choice Questions (MCQs)

    • A collection of questions testing the reader's understanding of concepts and calculations related to heat, phase changes, and specific heat capacity of different materials.. Examples of specific heat capacity calculations, and various problems.

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    Related Documents

    Lecture 7: Quantity of Heat PDF

    Description

    Explore the concepts of specific heat and latent heat through this quiz. Understand the calculations for heat energy during phase changes and learn about the properties of various substances. Test your knowledge on how heat affects temperature change and state transitions in materials.

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