IB Chemistry R1.1 Measuring Enthalpy Change Key Definitions

Activation energy ($E_a$) is the minimum energy required for colliding particles to form an activated complex (also known as the transition state) and proceed to products.

A calorimeter is an apparatus designed to measure temperature changes, which can then be used to calculate the heat transferred during a reaction.

Energy is absorbed by the system from the surroundings, decreasing the temperature of the surroundings.

The enthalpy change (ΔH) of a reaction quantifies the heat exchanged at constant pressure during a chemical or physical change.

Energy is released from the system into the surroundings, increasing the temperature of the surroundings.

Heat is the energy transferred between a system and its surroundings due to a temperature difference.

Surroundings are everything outside the system that interacts with it (e.g., the reaction flask, water bath, or air).

The system is the specific part of the universe under study (e.g., the reactants and products involved in the reaction).

Temperature measures the average kinetic energy of the particles in a system.