Definitions

Objectives

1. Definition of terms which are necessary before we move into the discussion of the first law

2. A reference for later sections

Note: Other terms will be defined as they are needed.

Steady-State: No change with respect to time; There may however, be change with respect to position

System: Whatever we are interested in; For example: an engine, a reactor, or a living cell

State: A set of conditions which completely define a system; A state is given by its volume, temperature, pressure, and amount (moles) or mass

Extensive Property: A property dependent on the amount of material; For example, total volume: if we add two 250 mL cups of water together we get 500 mL of water

Intensive Property: A property not dependent on the amount of material; For example, temperature: if we add two 250 mL cups of 30 ° C water together the result is 30 ° C water, not 60 ° water

Pressure: Force divided by the surface area it is applied to; SI^[2]unit is the Pascal (Pa) = 1 N/m²

Standard State Pressure: 1 bar; 1 bar = 10⁵ Pa; previously 1 atmosphere (atm) was used -- 1 atm = 1.1013 bar

Notes

↑ Some people have learned the definition of equilibrium as "equal and opposite change". That definition is correct for some fields of study; however, in thermodynamics we are only interested in system as a whole -- not what is going on inside the system.
For example, look at a membrane with equal concentrations on both sides. There is movement across the membrane with equal amounts going each direction. However, if we only look at the system from the outside, nothing is changing.
↑ Système Internationale d'Unités, commonly know as the metric system. In science it is the normally accepted unit system

Thermodynamics
Introduction	What is this thing called Thermodynamics??? \| Definitions \| Thermal Equilibrium and Zeroth Law \| Limitations
First Law	Work, Heat, Energy, and the First Law \| Work, Heat, Energy, and the First Law (simplied) \| Derivatives \| Derivatives Exercise \| Reversibility, Enthalpy, and Heat Capacity
Second Law	Things to Think About \| Observations and Second Law of Thermodynamics \| Alternative Approach - the Clausis Inequality \| Consequences of the Second Law \| Consequences of the Second Law (simplified) \| Carnot Principle - motivation and examples \| Equivalence of Second Law Statements*
Third Law	Third Law of Thermodynamics \| Consequences of Third Law*
Development of Thermodynamics	The Thermodynamic Network \| Network Exercise \| Equations of State (EOS) \| EOS Example, Reading Tables, and Numerical Analysis \| EOS Exercises \| Thermochemistry
* Optional Section