Chapter 15 - The Laws of Thermodynamics

ΔS

________= T Where Q is the heat added and T is a constant temperature in a system in kelvin • Since processes are not reversible, Q in the equation can not be negative and thus change in entropy is always positive • The second law of thermodynamics in terms of entropy is: The entropy of an isolated system never decreases.

QL

Where ________ is the heat delivered to the inside of the house SEER Rating • SEER stands for seasonal energy efficiency ratio, it is similar to the COP of a device, defined as.

Thermodynamics

The study of processes in which energy is transferred as heat and as work.

The First Law of Thermodynamics

The change in internal energy of a closed system, ∆U , willbe equal to the energy added to the system by heating minus the work done by the system on thesurroundings

State Variables

Variables that describe the state of a system, these are energy U, pressure P, volumeV, temperature T, and mass M or number of moles n

Isothermic Process

A process that occurs at a constant temperature

Adiabatic Process

A process where heat does not flow in or out of a system, or it is so well insulated that heat does not get the chance to flow out, Q=0

Isobaric

A process where pressure is kept constant

Isovolumetric

A process where volume is kept constant

Metabolism

The energy changing processes in an organism

Second Law of Thermodynamics

Heat can flow spontaneously from a hot object to a cold object; heat wil not flow spontaneously from a cold object to a hot object

Heat Engine

A device that changes thermal energy to mechanical work

Operating Temeratures

The high temperature input and lower temperature output of a heat engine

Working Substance

The work heated to work, usually either steam or fuels such as gasoline

Efficiency

The ratio of the work a heat engine does and the input at the high temperature

Carnot Engine

Named after French scientist Sadi Carnot, this is the ideal engineer but it does actually exist

The Third Law of Thermodynamics

No device is possoble whose sole effects is to transform a given amount of heat completely into work

Entropy

A function of the state of a system, it goes along with temperature, volume, pressure, and mass

Heat Death

The prediction that all energy in the universe will, at some point, convert to heat energy

Microstate

Specifies the position and velocity of every particle in a system

Macrostate

Gives visible scale states of the system, such as temperature and pressure

Thermal Pollution

The thermal energy output by every heat engine, must be absorbed by the environment, which alters the Earth’s ecology

Air Pollution

Chemicals put into the air by burning fuels, mainly in the form of Carbon Dioxide, CO2

Carbon Footprint

Refers to the negative impact of an activity by how much carbon dioxide it releases