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Heat and temperature

Chemistry • Energy & Heat in Chemical Processes • Knowledge-Based • 5 questions

Heat and temperature Knowledge-Based Download PDF

Chemistry · Thermochemistry & Thermodynamics · Chemistry · Energy & Heat in Chemical Processes

5 Chemistry practice questions on Heat and temperature. Questions that assess core concepts and understanding.

Questions

  1. 1.

    Which statement correctly distinguishes the heat capacity of an object from the specific heat capacity of the material composing it?

    • A) Heat capacity depends solely on the chemical composition of the substance, whereas specific heat capacity depends directly on the total mass of the object.
    • B) Heat capacity is an intensive property expressed in J/(g·K), whereas specific heat capacity is an extensive property expressed in J/K.
    • C) Heat capacity is an extensive property that depends on the mass of the object, whereas specific heat capacity is an intensive property characteristic of the material itself.
    • D) Heat capacity represents the energy transferred during a phase change at constant temperature, whereas specific heat capacity represents the energy transferred during a temperature change.
  2. 2.

    When heat is continuously supplied to a pure solid substance at its normal melting point, the temperature of the solid-liquid mixture remains constant until melting is complete. Which of the following statements correctly explains why the temperature does not change during this process?

    • A) The absorbed thermal energy is used to overcome intermolecular attractions and increase potential energy rather than increasing the average kinetic energy of the particles.
    • B) The absorbed thermal energy is completely dissipated to the surroundings so that the total internal energy of the substance remains unchanged.
    • C) The heat capacity of the substance becomes zero at the melting point, preventing any transfer of kinetic energy between molecules.
    • D) The absorbed heat breaks covalent intramolecular bonds, converting the solid into completely isolated gaseous atoms before liquid forms.
  3. 3.

    Two separate samples of pure liquid water, Sample X (100 g) and Sample Y (500 g), are both held at a uniform temperature of 25 °C. Which statement correctly compares the average kinetic energy of their molecules and the quantity of heat required to raise the temperature of each sample by 5 °C?

    • A) The molecules in both samples have the same average kinetic energy, but Sample Y requires five times as much heat as Sample X to achieve the temperature increase.
    • B) The molecules in Sample Y have a greater average kinetic energy, and Sample Y requires five times as much heat as Sample X to achieve the temperature increase.
    • C) The molecules in both samples have the same average kinetic energy, and both samples require the exact same quantity of heat to achieve the temperature increase.
    • D) The molecules in Sample X have a greater average kinetic energy, but Sample Y requires five times as much heat as Sample X to achieve the temperature increase.
  4. 4.

    When two closed systems at different initial temperatures are placed in thermal contact inside an insulated container, which condition fundamentally characterizes the state of thermal equilibrium?

    • A) The total internal energy is divided equally between the two systems regardless of their masses.
    • B) Heat transfer continues in both directions until the total thermal energy of each system drops to zero.
    • C) Net heat transfer ceases because the systems reach a uniform temperature corresponding to the same average kinetic energy per particle.
    • D) Both systems exhibit identical heat capacities, preventing further energy exchange between them.
  5. 5.

    Which of the following statements correctly distinguishes heat from temperature in chemical thermodynamics?

    • A) Temperature is an extensive property that depends on the quantity of matter, whereas heat is an intensive property independent of mass.
    • B) Heat is a state function that quantifies the average kinetic energy of particles, whereas temperature measures the total energy transferred between bodies.
    • C) Temperature is an intensive property proportional to the average kinetic energy of particles, whereas heat is the thermal energy transferred between systems due to a temperature difference.
    • D) Heat is the total internal energy contained within a system at equilibrium, whereas temperature is the energy released during a phase change.