5.1 Thermal Physics

Thermal Equilibrium

Two objects are in contact with each other at the same temperature

Heat

The transfer of thermal energy from regions of higher temperature to regions of lower temperature

Temperature

Measure of the average kinetic energy of the particles in a substance and determines the direction heat flow

T(K)=

Tc+273

Molecule

Smallest particle of a pure substance that is a characteristic of the substance

Atom

The smallest particle of an element that is characteristic of the element

Kinetic Model: Solid

The particles vibrate in a fixed ordered lattice. If the temperature is increased, the amplitude of the vibration increases

Kinetic Model: Liquid

The particles can flow past one another. They are vibrating but the vibration is not around a fixed point

Kinetic Model: Gas

The particles are far apart. They don't exert forces on each other except during a collision. The particles move in a random linear motion

Brownian Motion Cause: movement of smoke particles are random

Brownian Motion Effect: b/c of collisions with randomly moving air molecules

Brownian Motion Cause: Smoke particles are visible but air molecules are not

Brownian Motion Effect: Air molecules must be small

Brownian Motion cause: Smoke particles are moving in random linear motion

Brownian Motion Effect: b/c air particles are moving in random linear motion

Internal Energy

The sum of the randomly distributed kinetic and potential energies of the particles in a given system

Absolute Zero

The lowest temperature possible. Internal energy is a minimum

Specific Heat Capacity

The energy required to raise the temperature of 1kg of the substance by 1C

Specific Latent Heat

The energy required per kilogram of the substance to change its state without any change in temperature

Specific Latent Heat of Fusion

The energy which must be supplied to cause 1kg of a substance to melt at a constant temperature

Specific Latent Heat of Vaporisation

The specific latent heat for change between a liquid and a gas.

One Mole of a Substance

The amount of that substance which contains the same number of particles as there are atoms in 0.012kg of carbon-12

Kinetic Theory of Gases Assumptions

- Large number of identical particles in a state of rapid, random motion

- Particles occupy negligible volume compared to the volume of gas

- All collisions are perfectly elastic and the time of the collisions is negligible compared to the time between collisions

- Negligible forces between particles except during collisions

Boyle's Law

The pressure exerted by a fixed mass of gas is inversely proportional to its volume, provided that the temperature of the gas remains constant

Maxwell-Boltzmann distribution

Shows the spread of energies that molecules of gas or liquid have at a particular temperature