Thermochemistry

System

What we’re looking at in a chemical equation (reactants & products)

Energy is potential, and stored in chemical bonds.

Surroundings

Everything outside the system.

Energy is kinetic, therefore is temperature.

What is the relationship between system and surroundings?

Energy flows between them.

If one loses energy, it is recieved by the other.

Energy

E, ability to do work

Enthalpy

𝝙H, in kJ measure of the total energy in a thermodynamic system, accounting for pressure and volume [needs expanding]

Kinetic energy

E_k, energy of motion. Found in surroundings in the form of temperature.

Potential energy

E_p. Found in chemical bonds int the system.

Temperature

Average kinetic energy of the particles

Themal energy

Total kinetic energy of the particles.

Heat

Transfer of thermal energy (hot→cold)

Breaking bonds _______ energy

requires

Forming bonds _______ energy

releases

Exothermic

Energy is a product.

More energy is released forming bonds than is required to break bonds.

𝝙H is negative because the system is losing energy.

Endothermic

Energy is a reactant.

More energy is required to break bonds than is released to form bonds.

𝝙H is positve because the system is gaining energy