Thermodynamics Vocab Flashcards

Terms Definitions
Slants
ΔH=mCpΔT
ΔS=q/T
Entropy equation
combustion reaction
exothermic
k
1.38 x 10^-23
Standard Conditions
1atm; 25°C
KiloCalories
1000 cal
food calories
Interphase
3 stages (non dividing)
ΔU=q+w
The first law equation
density
mass per unit volume
Convected energy
(see flow work).
System releases energy
(ΔE)
Negative (-)
R
ideal gas law constant .0821
entropy
deltaS measure of disorder/randomness in units of energy/temperature (J/K) higher temp=higher entropy
endergonic
If ΔG>0 the reaction is
fat
unused carbs are stored as
Potential energy
energy that is stored
Thermodynamics
concerned with the quantitative relationships between heat and other forms of energy, such as: mechanical, chemical, electric, and radiant energy
Energy and Work
Force times distance
Heat capacity of solid water
2.1 J/gC
A quasiequilibrium process is also called a ____________ process.
quasistatic
state function
What properties are in capitals
endothermic
energy flows from surroundings to system
exothermic
releases heat (negative change in energy)
Free Energy
energy available to do work
Formal sign convention
(classical thermodynamics sign convention) for heat and work interactions is as follows: heat transfer to a system and work done by a system are positive; heat transfer from a system and work done on a system are negative.
Calorimetry
the measure of heat-related constants, such as specific heat or latent heat
process
a method of chemically straightening the hair.
2ed law
everything is moving toward thermal equilibrium
black body
a hypothetical object capable of absorbing all the electromagnetic radiation falling on it. Also a perfect radiative emitter.
ΔG⁰=-RTlnK
What is the equation linking gibbs energy and the equilibrium constant?
Thermal Conductor
A material that conducts thermal energy well
Nuclear Energy
Nuclear energy is the energy associated with nuclear bonding of the nucleus of an atom.
Closed System
Not matter exchange; heat exchange (constant mass, changing energy).
Path functions
are functions whose magnitudes depend on the path followed during a process as well as the end states.
Fuel cells
operate on the principle of electrolytic cells in which the chemical energy of the fuel is directly converted to electric energy, and electrons are exchanged through conductor wires connected to a load. Fuel cells are not heat engines, and thus their efficiencies are not limited by the Carnot efficiency. They convert chemical energy to electric energy essentially in an isothermal manner.
Dry-bulb temperature
is the ordinary temperature of atmospheric air.
Turboprop engine
uses propellers powered by the aircraft turbine to produce the aircraft propulsive power.
Wasted work potential
represents irreversibility as the energy that could have been converted to work but was not and is the lost opportunity to do work.
Isothermal
process in which the temperature is kept constant during the reaction; system is surrounded by a constant temperature bath; heat is exchanged without the change of temperature
which law states that the internal energy of a system is constant?
first
Heat
Transfer of energy from one object to another
Thermal Energy
total amount of energy associated with the random movement of atoms and molecules in a sample of matter
Mueller's Ratchet
Asexual reproduction cannot get rid of mutations, instead passes them on.Sexual reproduction evolved in away to reduce the mumber of mutations passes to fuuter offspring.
adiabatic
no heat enters or leaves the system (no Q); any energy added to the system is work being done on it
hess's law
states the overall enthalpy change in a reaction ie equal to the sum of enthalpy changes for the indiv. steps in the process
A spontaneous reaction
occurs immediately as the reactants are mixed
Isolated system
No energy transfer takes place with surroundings
surroundings
where does heat lost in a reaction go
Intrinsic Observation
Observation of the system that is obtained without reference to the surroundings
Reversible (Quasi-Static)
Process where, at end of complete cycle, both system and surroundings have been returned to initial states w/o permanent changes.
Thermochemistry
the study of heat energy in chemical reactions
Thrust
is the unbalanced force developed in a turbojet engine that is caused by the difference in the momentum of the low-velocity air entering the engine and the high-velocity exhaust gases leaving the engine, and it is determined from Newton's second law.
Flow exergy
results from mass entering or leaving a system and carries exergy per unit mass in the amount y = (h - h0) - T0(s - s0) + / 2 + gz with it. Therefore, the exergy of a system increases by y when mass enters, and decreases by the same amount when mass at the same state leaves the system.
Sublimation line
separates the solid and vapor regions on the phase diagram.
Cycle
is a process, or series of processes, that allows a system to undergo state changes and returns the system to the initial state at the end of the process. That is, for a cycle the initial and final states are identical.
Refrigerant
is the working fluid used in the refrigeration cycle.
equation of state
provides a relationship among values in a system. for example, the ideal gas law: pV=nRT
thermal equilibrium
condition in which two substances in physical contact exchange no heat energy
First Law of Thermodynamics
The principle of conservation of energy. Energy can be transferred and transformed, but it cannot be created or destroyed. change in system's internal energy = Q - W
Mass will not cross the boundary of a control volume. True or False
False
open system
can have free movement of both energy and matter
Extensive Property
a property that depends on the amount of matter in a sample
Zeroth Law of Thermodynamics
Two systems individually in thermal equilibrium with a third system are in thermal equilibrium with each other
What is an example of low entropy (high quality)?
Chemical energy
Entropy transfer
is the transfer of entropy across a boundary by heat or mass.
Reversible workWrev
is defined as the maximum amount of useful work that can be produced (or the minimum work that needs to be supplied) as a system undergoes a process between the specified initial and final states. Reversible work is determined from the exergy balance relations by setting the exergy destroyed equal to zero. The work W in that case becomes the reversible work.
Inversion line
is the line that passes through the points of zero slope of constant-enthalpy lines or zero Joule-Thomson coefficient on the T-P diagram. The slopes of the h = constant lines are negative (μJT < 0) at states to the right of the inversion line and positive (μJT > 0) to the left of the inversion line.
Pressure
is defined as the force exerted by a fluid per unit area.
Gibbs's Free Energy
A thermodynamic quantity that is the difference between the enthalpy and the product of the absolute temperature and entropy of a system. Also called Gibbs free energy
if e is uniform in control volume:
peVol = mass*e
What is a state variable?
Variables that are uniquely determined by the current state of the system. Tell you the properties of the system at a given point in time not how they got you. Can look at how state variables changes. Example for dry air: temperature, pressure, density. Not state variables: heat consumed, distance traveled.
Internal Energy
the sum of the all the kinetic and potential energies of all particles in the system
heat of combustion
amount of energy released as heat by the complete combustion of 1 mol of a substance
Third law of thermodynamics
The entropy of a pure crystalline substance is zero at absolute zero (or -273.16 °C)
Quasi-Equilibrium Process
A process in which all the states the system passes through may be considered as equilibrium states. (This implies that the process is done slowly and that the gas pressure is uniform throughout the system)
Second law of thermodynamics
asserts that energy has quality as well as quantity, and actual processes occur in the direction of decreasing quality of energy.
Reversible steady-flow work
is defined as the negative of the integral of the specific volume-pressure product. The larger the specific volume, the larger the reversible work produced or consumed by the steady-flow device. Therefore, every effort should be made to keep the specific volume of a fluid as small as possible during a compression process to minimize the work input and as large as possible during an expansion process to maximize the work output.
Electrical power
is the rate of electrical work done as electrons in a wire move under the effect of electromotive forces, doing work. It is the product of the potential difference measured in volts and the current flow measured in amperes.
Heat Capacity (C)
the amount of heat required to raise the temperature of 1 mole of substance 1 degree; = Q/ΔT = dQ/dT
1st law of thermodynamics.
Heat added=
increase internal energy + External work done by system
reactants
At equilibrium if K < 1 then lnK is -, and there will be more _________
What is a lapse rate?
At any given altitude, defined as local rate of decrease of temperature with altitude: Γ= -T2-T1/ z2-z1.
Briefly explain the microscopic interpretation of Internal Energy.
Thinking of the energy attributed to the motions and configurations of the individual molecules, atoms, and subatomic particles making up the matter in the system.
1st Law of Thermodynamics
the law that states that energy cannot be created nor destroyed
Conservation of energy principle
or energy balance based on the first law of thermodynamics may be expressed as follows: Energy can be neither created nor destroyed; it can only change forms. The net change (increase or decrease) in the total energy of the system during a process is equal to the difference between the total energy entering and the total energy leaving the system during that process. The energy balance can be written explicitly as
What is the Celcius temperature scale?
Every other country uses except for the United States, temperature on upper level air maps, research articles. C=K-273.15 Freezing point is 0°C and boiling point is 100 °C.
Thermodynamics is the branch of science that
examines the various process and the energy changes that accompany the process
Conservation of mass principle for combustion (or the mass balance)
is the principle used to balance chemical reaction equations. It can be stated as the total mass of each element is conserved during a chemical reaction. The total mass of each element on the right-hand side of the reaction equation (the products) must be equal to the total mass of that element on the left-hand side (the reactants) even though the elements exist in different chemical compounds in the reactants and products. Even though the mass must be conserved, the total number of moles is not necessarily conserved during a chemical reaction.
What does the hypsometric tell us?
Helps us find the thickness of the atmospheric layer bounded by those pressure levels.
the number of states and, therefore, the entropy tends to increase with increases in:
temperature, volume (gases), and the # of independently moving molecules
Specific heat at constant pressure Cp
is the energy required to raise the temperature of the unit mass of a substance by one degree as the pressure is maintained constant. Cp is a measure of the variation of enthalpy of a substance with temperature. Cp can be defined as the change in the enthalpy of a substance per unit change in temperature at constant pressure.
why do standard entropies tend to increase with increasing molar mass?
they have more electrons, so there is more movement (randomness, disorder)
When can we use the ideal gas law?
It is valid whenever the density of the gas is low enough (due to a suitable combination of low pressure and high temperature) that individual molecules do not experience significant attractive forces nor does the space occupied by the molecules represent a significant fraction of the total volume. At ordinary atmospheric pressures, air obeys the Ideal Gas Law quite closely for almost all meteorological purposes.
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