Specific Heat Capacity and Thermal Expansion
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Questions and Answers

What is the unit of specific heat capacity?

  • Joule per kilogram
  • Kelvin per kilogram
  • Joule per kilogram per Kelvin (correct)
  • Kelvin per Joule per kilogram

    • What is the significance of a high value of heat capacity?

  • The substance does not absorb or release heat energy.
  • The temperature of a substance does not change even when heat energy is added.
  • A low amount of heat energy is required to change the temperature of a substance.
  • A high amount of heat energy is required to change the temperature of a substance. (correct)

    • Why is water used in automobile radiators as an efficient coolant?

  • Because it has a high specific heat capacity. (correct)
  • Because it is inexpensive.
  • Because it has a low specific heat capacity.
  • Because it is readily available.

    • What is the difference between molar heat capacity at constant pressure and molar heat capacity at constant volume?

    <p>The pressure of the gas is kept constant in one and the volume is kept constant in the other.</p> Signup and view all the answers

    What is the specific heat ratio or adiabatic index?

    <p>The ratio of molar heat capacity at constant pressure to molar heat capacity at constant volume.</p> Signup and view all the answers

    Why does water have a high specific heat capacity?

    <p>Because it can absorb a substantial amount of heat energy.</p> Signup and view all the answers

    A 100g block of metal at 100°C is placed in a calorimeter containing 200g of water at 20°C. If the final temperature of the system is 25°C, what is the specific heat capacity of the metal? (Specific heat capacities of water and calorimeter are 4.18 J/g°C and 0.4 J/g°C respectively)

    <p>0.21 J/g°C</p> Signup and view all the answers

    Which of the following statements is true about the specific heat capacity of a substance?

    <p>It is the amount of heat required to raise the temperature of 1 gram of the substance by 1 degree Celsius.</p> Signup and view all the answers

    What is the primary factor that determines the amount of heat needed to raise the temperature of a substance?

    <p>The mass of the substance</p> Signup and view all the answers

    Which of the following is NOT a type of thermal expansion?

    <p>Density expansion</p> Signup and view all the answers

    What happens to the lid of a jam jar when it is heated?

    <p>The lid expands, making it easier to remove</p> Signup and view all the answers

    What is the primary reason why a thermometer uses mercury?

    <p>Mercury expands significantly with temperature changes.</p> Signup and view all the answers

    What is the difference between heat capacity and specific heat capacity?

    <p>Heat capacity is the amount of heat needed to raise the temperature of a substance by one unit, while specific heat capacity is the amount of heat needed to raise the temperature of one gram of a substance by one unit.</p> Signup and view all the answers

    Which of the following is NOT a factor that affects the heat capacity of a substance?

    <p>The color of the substance</p> Signup and view all the answers

    What is meant by thermal expansion?

    <p>The change in dimensions of an object due to temperature change.</p> Signup and view all the answers

    Which factor is NOT considered when determining the heat capacity of a substance?

    <p>Volume of the substance</p> Signup and view all the answers

    How does the specific heat capacity of a substance relate to its mass?

    <p>Specific heat capacity is defined as heat required per unit mass.</p> Signup and view all the answers

    What happens to the mercury in a thermometer when the temperature of its surroundings increases?

    <p>The mercury expands and rises in the thermometer column.</p> Signup and view all the answers

    In which scenario would you expect the heat capacity of a substance to be highest?

    <p>When the substance has a high thermal inertia.</p> Signup and view all the answers

    Which of the following describes linear thermal expansion?

    <p>Expansion in the length of an object.</p> Signup and view all the answers

    Which of the following substances has the highest specific heat capacity?

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

    What is the primary interpretation of a substance having a high heat capacity?

    <p>It requires a high amount of heat energy to change its temperature by a certain degree</p> Signup and view all the answers

    What is the significance of the molar specific heat capacity of gases?

    <p>It is a measure of the heat required to raise the temperature of a gas by one unit</p> Signup and view all the answers

    What determines the type of molar specific heat capacity of gases?

    <p>The volume of the gas</p> Signup and view all the answers

    What is the relation between the specific heat capacity of a substance and its temperature change?

    <p>The temperature change determines the specific heat capacity</p> Signup and view all the answers

    Why does water have various applications?

    <p>Due to its high specific heat capacity</p> Signup and view all the answers

    What is the correct formula to calculate the specific heat capacity of a substance?

    <p>$c = \frac{Q}{m \Delta T}$</p> Signup and view all the answers

    When two systems at different temperatures interact to reach a steady state, what happens to the heat lost by one system?

    <p>It is equal to the heat gained by the other system</p> Signup and view all the answers

    What is the primary factor that determines the specific heat capacity of a substance?

    <p>Nature of the substance</p> Signup and view all the answers

    Why is a mercury thermometer preferred over an ethyl alcohol thermometer to measure the body temperature of an infant?

    <p>Mercury has a lower specific heat capacity than ethyl alcohol</p> Signup and view all the answers

    Which material will have a higher temperature rise when supplied with the same amount of heat?

    <p>One with a lower specific heat capacity</p> Signup and view all the answers

    If two materials A and B of equal mass are supplied with the same amount of heat, and the temperature rise in A is found to be more than that in B, which material has a higher specific heat capacity?

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

    What is the correct formula to calculate the heat gained by a substance?

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

    Which of the following statements is true about the specific heat capacity of a substance?

    <p>It is a constant for a given substance</p> Signup and view all the answers

    Study Notes

    Heat and Its Effects

    • Heat is energy transferred between systems due to temperature differences.
    • Thermal expansion occurs when heat causes an increase in an object's dimensions, which includes:
      • Linear expansion: Change in length
      • Area expansion: Change in area
      • Volume expansion: Change in volume
    • Mercury in thermometers expands or contracts based on surrounding temperature changes.

    Heat Capacity and Specific Heat Capacity

    • Heat capacity depends on:
      • Temperature difference
      • Mass of the substance
      • Nature of the substance
    • Heat capacity is the total heat required to change a substance's temperature by one degree.
    • Specific heat capacity is the heat required to change the temperature of unit mass of a substance by one degree, crucial for understanding temperature changes without state changes.
    • Specific heat capacity units: Joule per kilogram per Kelvin (J/kg·K).

    High and Low Heat Capacity

    • Materials with high heat capacity require more energy to change temperature, absorbing or releasing significant heat.
    • Materials with low heat capacity necessitate less energy and thus change temperature more rapidly.
    • Water has a notably high specific heat capacity of 4186 J/kg·K, making it an effective heat regulator and coolant, influencing climate and providing heat storage in applications.

    Molar Heat Capacity of Gases

    • Molar heat capacity can be defined per mole of a substance, distinguished by:
      • Constant pressure (Cᵖ)
      • Constant volume (Cᵑ)
    • The specific heat ratio (γ) is greater than 1, reflecting the higher heat capacity needed at constant pressure compared to constant volume.

    Calculating Specific Heat Capacity

    • The specific heat capacity formula relates heat supplied (Q), mass (m), and temperature change (ΔT):
      • ( C = \frac{Q}{m \cdot \Delta T} )
    • Heat lost by one system equals heat gained by another in thermodynamic interactions.

    Examples of Specific Heat Calculations

    • Heat loss or gain equations can be set up involving known specific heat capacities to estimate unknown values in various materials.

    Understanding Through Application

    • When two equal mass materials receive the same heat, the material with the greater temperature rise has a lower specific heat capacity.
    • For precise temperature measurements, using substances with lower specific heat capacities, like mercury, minimizes heat absorption from the body.
    • Calculating whether more heat is needed to raise the temperature of ice versus water depends on their specific heat capacities, with water requiring more heat due to higher capacity values.

    Heat and Its Effects

    • Heat is energy transferred between a system and its surroundings due to temperature differences.
    • Thermal expansion occurs when heat causes materials to change dimensions:
      • Linear expansion: changes in length
      • Area expansion: changes in area
      • Volume expansion: changes in volume
    • An example of thermal expansion is seen in mercury thermometers, where the volume of mercury fluctuates with temperature changes.

    Heat Capacity and Specific Heat Capacity

    • Heat capacity is dependent on the temperature difference, mass, and nature of the substance.
    • Specific heat capacity is the heat required to change the temperature of unit mass of a substance by one unit.
    • Specific heat capacity equations account for mass and temperature change but not state changes in the substance.
    • The SI unit for specific heat capacity is Joules per kilogram per Kelvin (J/kg·K).

    High and Low Heat Capacity

    • High heat capacity indicates substantial heat energy is needed for temperature changes, while low heat capacity indicates less energy is needed.
    • Specific heat capacities of common substances:
      • Water: 4186 J/kg·K (high)
      • Aluminium: 900 J/kg·K
      • Carbon: 506.5 J/kg·K
      • Ice: 2060 J/kg·K
      • Edible oil: 1965 J/kg·K
      • Mercury: 140 J/kg·K
    • Water's high specific heat capacity results in various applications like regulating temperatures in environments and being used in cooling systems.

    Molar Heat Capacity of Gases

    • Molar specific heat capacity is defined as heat capacity per mole of substance.
    • Two conditions for gases:
      • Molar specific heat capacity at constant pressure (Cp)
      • Molar specific heat capacity at constant volume (Cv)
    • The specific heat ratio (Cp/Cv) is always greater than 1 because it requires more heat to raise the temperature at constant pressure compared to constant volume.

    Calculating Specific Heat Capacity

    • Specific heat capacity can be calculated using the formula: ( c = \frac{Q}{m \Delta T} )
    • When two systems at different temperatures interact, heat lost by one equals heat gained by the other.

    Examples and Applications

    • Problem-solving involves equating heat lost by a warmer body with heat gained by a cooler body to find unknown specific heats.
    • Specific heat capacity influences real-world applications, such as:
      • Mercury thermometers absorb less heat for temperature measurement compared to ethyl alcohol thermometers.
      • Energy calculations for heating ice versus water, noting the larger heat required for water due to its higher specific heat capacity compared to ice.

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    Learn about the effects of heat on matter, including thermal expansion and its practical applications.

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