Chem 1000: Thermochemistry Introduction

TERMINOLOGY

A universe is comprised of a system and its surroundings.

• SYSTEM: Part of universe chosen to be studied
• SURROUNDINGS: Part of the universe outside the system with which it interacts

Now there are three types of systems:

1. OPEN SYSTEM : Can freely exchange energy and matter with its surroundings
2. CLOSED SYSTEM: Can exchange energy but not matter with its surroundings
3. ISOLATED SYSTEM: Does not exchange matter or energy with its surroundings

ENERGY is the capacity to do work. WORK is done when a force acts through a distance.
There are two types of energy:

1. KINETIC ENERGY : The energy of a moving object which is calculated through the product of an object's mass and velocity
• Kinetic energy associated with the random molecular motion is called THERMAL ENERGY
• Thermal energy is proportional to the temperature of a system.
• The more vigorous the motion of the molecules of the system, the hotter the sample and the greater its thermal energy
2. POTENTIAL ENERGY : The stored energy has the potential to do work when released