Physical Chemistry/Introduction to Thermodynamics

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Thermodynamics is a misnomer since we will only consider equilibrium phenomena, not time-dependence like in kinetics. Thermodynamics deals with things like energy, entropy, volume, heat, work, efficiency (ideal), free energy, chemical potential, pressure, temperature. It was developed to explain steam engines back in the 1800's. It has come a long way since then, able to explain a vast array of phenomena in chemistry, physics, and biology. It is an old, but beautiful theory. It is important in chemistry.

Sample problem

An ideal monoatomic gas at 1 bar is expanded in a reversible adiabatic process to a final pressure of bar. Calculate per mole, per mole, and .

To solve this, we need to apply the fact that .

So, substitute and solve for

Now, we use

Which will give us

Hence, we have all of our answers...

Adiabatic means , so and while

The Zeroth Law of Thermodynamics[edit | edit source]

This law of thermodynamics was developed after the establishment of the first and second laws of thermodynamics. The law is involved in defining temperature.

Let us consider three systems, A, B, and C. If systems A and C are in equilibrium, and B and C are in equilibrium, then A and B will be found to be in thermal equilibrium when connected by a heat conductor. This associative property of systems is the Zeroth Law of Thermodynamics.

The Zeroth Law of Thermodynamics states that if two systems are in thermodynamic equilibrium separately with a third system then both these systems are said to be in thermodynamic equilibrium with each other.