Calorimetry

Building on our understanding of thermochemistry and heat capacity, this episode delves into **Calorimetry**, the practical science of measuring heat flow. We will explore how scientists quantify the energy released or absorbed during a chemical reaction. You will learn about the design and function of two major types of calorimeters: the simple coffee-cup calorimeter used for reactions in solution, and the robust bomb calorimeter used for combustion reactions. This episode provides the experimental foundation for understanding reaction energies, revealing how we measure the very data that underpins thermochemistry.

Check your understanding

These are the same multiple-choice questions you will see in the Quiz section after you listen to the episode. Use them here to preview or review the answers.

What is the fundamental principle behind how calorimetry works?

  1. The heat released or absorbed by a reaction can be determined by measuring the temperature change of its isolated surroundings.
  2. All chemical reactions release heat into the environment.
  3. The speed of a reaction is directly proportional to the heat it produces.
  4. Heat and temperature are the same physical quantity.
  5. Chemical reactions only occur at constant pressure.

In a coffee cup calorimeter experiment, you dissolve a salt in water and the temperature of the water rises from 25°C to 28°C. What can you conclude about this process?

  1. The process of dissolving the salt was endothermic.
  2. The process of dissolving the salt was exothermic.
  3. The heat of the reaction (q_reaction) is a positive value.
  4. The heat absorbed by the water (q_solution) is a positive value.
  5. No heat was exchanged.

A bomb calorimeter is the preferred instrument for measuring the heat change of which type of process?

  1. The neutralization of an acid with a base in solution.
  2. The melting of a solid.
  3. The combustion of a fuel.
  4. The dissolving of sugar in tea.
  5. A precipitation reaction between two aqueous solutions.

The calculation for a bomb calorimeter often uses the formula q = C_cal * ΔT. What does the term C_cal represent?

  1. The specific heat capacity of the water only.
  2. The change in temperature of the bomb.
  3. The total heat capacity of the entire calorimeter system (bomb, water, etc.).
  4. The constant pressure of the system.
  5. The chemical energy of the sample.

Which of the following are key features or assumptions associated with a constant-pressure "coffee cup" calorimeter?

  1. The reaction is carried out in a sealed, rigid steel container.
  2. It is assumed that no heat is lost to the outside environment.
  3. The pressure of the system remains constant.
  4. It is best suited for reactions in aqueous solutions.
  5. The heat change is measured at constant volume.

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