Heat Capacity and Calorimetry - AP Chemistry

1. What does the symbol $q$ represent in calorimetry equations?

   Heat absorbed or released. Standard symbol for heat energy in thermodynamic calculations.

2. How is heat exchange calculated for a system with phase changes?

   Sum of $q$ for temperature change and $q$ for phase change. Both sensible and latent heat contributions must be included.

3. List one assumption made in calorimetry experiments.

   No heat is lost to the surroundings. Ideal calorimeter assumption for simplified calculations.

4. How do you determine the heat of a reaction using a bomb calorimeter?

   Use $q_{\text{reaction}} = -C_{\text{cal}} \times \Delta T$. Uses total calorimeter heat capacity for precise energy measurement.

5. What is the main difference between a bomb calorimeter and a coffee cup calorimeter?

   Bomb calorimeter operates at constant volume, coffee cup at constant pressure. Different conditions affect which thermodynamic quantity is measured.

6. What does the symbol $C_{\text{cal}}$ represent in calorimetry?

   Heat capacity of the calorimeter. Standard notation for calorimeter's heat capacity.

7. What unit is used for measuring heat in calorimetry?

   Joules (J). Standard SI energy unit for all thermodynamic calculations.

8. What is the purpose of a bomb calorimeter?

   To measure the heat of combustion reactions. Specialized for high-energy combustion reactions requiring sealed conditions.

9. What is the formula for calculating $\triangle T$ in calorimetry?

   $\triangle T = T_{\text{final}} - T_{\text{initial}}$. Standard definition of temperature change in thermodynamics.

10. Which equation relates heat capacity to specific heat capacity?

    $C = m \times c$. Heat capacity equals mass times specific heat capacity.

11. What is the calorimeter constant?

    The heat capacity of the calorimeter itself. Accounts for heat absorbed by the calorimeter apparatus itself.

12. How do you find the calorimeter constant?

    $C_{\text{cal}} = \frac{q}{\triangle T}$ for the calorimeter. Determined by measuring heat and temperature change for the calorimeter.

13. What is the principle behind calorimetry?

    Heat lost by the system equals heat gained by the surroundings. Based on conservation of energy in thermal equilibrium.

14. What is the role of water in a coffee cup calorimeter?

    Acts as the medium absorbing or releasing heat. Water's high heat capacity makes it ideal for absorbing reaction heat.

15. Identify the relationship between internal energy and heat at constant volume.

    $\triangle U = q_{\text{v}}$. At constant volume, heat equals internal energy change.

16. Define specific heat capacity.

    The heat required to raise the temperature of 1 gram of a substance by 1°C. This is the definition of specific heat capacity, an intensive property.

17. How can you measure the specific heat capacity of an unknown metal?

    Use calorimetry to find $c$ from $q = m \times c \times \Delta T$. Heat known metal in calorimeter and measure temperature change.

18. What is the main assumption in a constant-pressure calorimeter?

    Pressure remains constant throughout the experiment. Open system allows pressure equilibrium with atmosphere.

19. How is the heat of solution determined using a calorimeter?

    Measure $\triangle T$ and calculate $q$ using solution mass and $c$. Dissolution process measured by temperature change of solution.

20. What is the equation for calorimetry involving a calorimeter constant?

    $q_{\text{reaction}} = -(q_{\text{water}} + q_{\text{cal}})$. Accounts for heat absorbed by both water and calorimeter.

21. How do you calculate the heat absorbed by water in a calorimeter?

    $q = m \times c \times \Delta T$. Same formula applies to any substance including water in calorimeters.

22. How do you find the specific heat capacity from experimental data?

    Use $c = \frac{q}{m \times \triangle T}$. Rearrangement of the basic calorimetry equation.

23. What is the primary function of a constant-volume calorimeter?

    To measure heat of reaction at constant volume. Bomb calorimeter operates under constant volume conditions.

24. What is the significance of a negative $q$ value in a calorimetry experiment?

    Indicates heat is released by the system. Negative sign indicates exothermic process with energy release.

25. What is the unit of specific heat capacity in the SI system?

    Joules per gram per degree Celsius (J/g°C). Standard SI units for energy per unit mass per temperature change.

26. What is the formula to calculate heat absorbed by a substance?

    $q = m \times c \times \triangle T$. Fundamental equation for calculating thermal energy transfer.

27. What is the formula for calculating heat using specific heat capacity?

    $q = m \times c \times \triangle T$. Where $q$ is heat, $m$ is mass, $c$ is specific heat, and $\triangle T$ is temperature change.

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

    Heat capacity is total heat required, specific is per gram. Heat capacity is extensive, specific heat is intensive property.

29. How is enthalpy change determined in a calorimetric experiment at constant pressure?

    $\triangle H = q_{\text{p}}$. At constant pressure, heat equals enthalpy change.

30. What is the formula for calculating energy change in a phase transition?

    $q = m \times \triangle H_{\text{transition}}$. Where $\triangle H_{\text{transition}}$ is the specific enthalpy of phase change.

31. Identify the formula for calculating heat capacity.

    $C = \frac{q}{\triangle T}$. Heat capacity is the ratio of heat absorbed to temperature change.

32. State the law of conservation of energy in the context of calorimetry.

    Energy cannot be created or destroyed; it is conserved. Fundamental principle stating total energy remains constant in isolated systems.

33. What is the function of a calorimeter?

    To measure the heat of chemical reactions or physical changes. Primary purpose is precise measurement of thermal energy changes.

34. What is a common use for calorimetry in chemistry?

    Determining enthalpy changes of reactions. Essential application for studying reaction thermodynamics.

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