Thermochemistry and Calorimetry

Key Concepts

• Thermochemistry: Study of heat transfer in chemical reactions or physical processes.
• System and Surroundings:
  • System: The part of the universe we want to study.
  • Surroundings: Everything else outside the system.

Types of Processes

• Exothermic Process:
  • Heat is released from the system to the surroundings.
  • Results in an increase in the temperature of the surroundings.
  • Initial temperature rises as the reaction equilibrates.
• Endothermic Process:
  • Heat is absorbed by the system from the surroundings.
  • Results in a decrease in the temperature of the surroundings.
  • Initial temperature drops as the reaction equilibrates.

Calorimetry

Coffee Cup Calorimeter

• Design:
  • Made of Styrofoam cups acting as insulators.
  • Includes a thermometer and a stirrer, sealed with a lid.
• Measurements:
  • Measures temperature change before and after reactions.
  • Operates at constant pressure.

Bomb Calorimeter

• Design:
  • Reaction takes place in a sealed inner vessel.
  • Operates at constant volume.
  • Heat from the reaction is absorbed or released by a surrounding liquid.
• Measurements:
  • Involves a heat capacity for the calorimeter.

Laws and Principles

Law of Conservation of Energy

• Energy can neither be created nor destroyed, only transferred.
• Total energy transfer in a system and its surroundings is zero.
• Equation: Q(system) + Q(surroundings) = 0

Analytical Approach

• Problem Solving:
  • Carefully read problems to identify relevant heat (Q) values.
  • The goal is to find the Q of the system under study.
  • Sum all Q values to zero, ensuring that the system's Q is accurately assessed.