Topic B

Temperature

Temperature

Average kinetic energy of particles in a substance.

Internal energy

Sum of intermolecular PE and random KE from all the particles in a substance.

Specific heat capacity

The amount of energy required to increase the temperature of 1 kg of a substance by 1 °C.

Conduction

Thermal energy flow through physical contact.

Convection

Movements of atoms in fluids because of variations in density.

Thermal radiation

Transfer of energy through electromagnetic radiation (doesn't need a medium to propagate).

Black Body

Absorbs all wavelengths of EM radiation and is a perfect emitter of radiation (poor reflector). Emissivity of 1 and albedo of 0.

Emissivity

Ratio of power radiated per unit area of an object compared to a perfect black body of the same temperature.

Albedo

The extent to which a surface can scatter energy.

Thermal equilibrium

When incident power equals power radiated.

Factors of climate change

Variable solar constant, albedo, emissivity (directly correlated to GHG), GHG (disrupt equilibrium, resonance).

GHG

CO2, H2O, methane, N2O.

Solutions

Reduce meat consumption, reduce deforestation, reduce air travel, use energy-efficient vehicles.

Boyle’s law

At a constant temperature, PV=constant.

Charle’s law

At a constant pressure, V/T=constant.

Gay-lussac’s a.k.a

At constant volume, P/T=constant.

Avogadro’s law

At constant temperature and pressure, n/v=constant.

Kinetic model of gas assumptions

Particles are undergoing constant random motion, particles are elastically colliding with each other and the walls of the container, the total volume of the particles is negligible compared to the volume of the container, external forces are ignored.

N

Number of molecules.

n

Number of moles.

Heat

Transfer of a quantity of thermal energy caused by a difference in temperature between a system and its surroundings.

Work

Macroscopic transfer of energy (positive work=expansion).

Heat engines

Convert energy into work.

Second law of thermodynamics

Energy cannot be extracted from a hot object and be transformed entirely into work.

Number of micro states

(# of possible outcomes)^(# of trials).

Electric potential difference

Work done per unit charge to move a positively charged particle from one point to another.

Thermistor

+T,-R,+P.

LDR

+I,-R,+P.