Principles of Chemistry I - Test #4: Thermodynamics

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111 Terms
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kinetic energy

-energy that something has because it is moving

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Kinetic energy depends on a particle's...

mass and velocity

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translation

3D movement of particles

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movement of particles in a solid

vibration or rotation

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potential energy

energy something has as a result of its position

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types of potential energy

structural or positional

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examples of potential energy

gravitational, electrostatic, chemical bond energy

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-E =

q+w

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internal energy

sum of all the individual energies of nanoscale particles in a system

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internal energy depends on...

temperature, type, and number of particles

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higher T =

higher energy

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Joule

1 kg m^2/s^2

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calorie

original energy unit, 4.184 J

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calorie definition

energy required to heat one gram of water one degree celsius

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system

the region of the universe we are studying

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surroundings

everything else, separated from the system by a boundary

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open system

exchanges both energy and matter with the surroundings

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closed system

exchanges energy but mot matter with the surroundings

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isolated system

neither energy nor matter is exchanged between the system and surroundings

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open system example

a glass of soda

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closed system example

a unopened can of soda

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isolated system example

capped thermos bottle

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equation for calculating thermodynamic change

deltaE = Efinal -Einitial

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state variable

depends only on the state of the system and is independent of how it got there

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path variable

depends on how the state was reached

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heat (q)

the energy associated with the translation, rotation, and vibration of molecules

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magnitude of delta T depends on...

q

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molar heat capacity (C)

accounts for the identity of a material and is intrinsic

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molar heat capacity synonym

heat capacity

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heat capacity equation

C=q/n deltaT

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specific heat capacity

quantity of heat required to raise the temperature of one gram of a substance by one degree K

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specific heat synonym

specific heat

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work (w)

energy used to move an object against an opposing force

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work=

force x displacement

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work units

N*m

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expansion work

w= -Pext x deltaVsystem

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First Law of thermodynamics

deltaEsys = qsys + wsys qsurrounding = -qsystem

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automobile engine

some heat is lost while doing expansion work

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automobile engine equation

deltaEstove = qengine + wengine

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gas stove

all energy is converted into heat

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gas stove equation

deltaEstove = qstove

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calorimetry

device that measures heat flow in a chemical reaction

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calorimetry equation

qsys = qcalorimeter + qchemical = 0

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constant pressure calorimeter

-most common way to measure heat flow -used in most labs -explains biological systems -open system

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constant volume calorimeter

-bomb calorimeter used to counteract large pressure increase -closed system

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enthalpy equation

H = E + PV deltaH = deltaE + PdeltaV

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heat of formation

heat required to produce of a single product from standard elements in standard condition

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Hess's Law

the enthalpy change for any process s the sum of the enthalpy changes for any set of steps leading up to it

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enthalpy is related to

intermolecular force strength

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lattice energy

the energy required to separate one mole of an ionic solid

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exothermic reactions tend to favor

products

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free energy

energy we can use to do work

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energy is more likely to spread...

over many particles rather than a few

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entropy

a measure of dispersed energy of a system

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how can we disperse energy/matter?

spread something into a larger volume or allow two items to reach thermal equilibrium

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mixing of miscible substances

spontaneous

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most probable mixing pattern of particles

has the most uniform distribution of particles thru the volume the particles occupy

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W

number of energy equivalent arrangements of particles

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entropy is proportional to...

number of possible arrangements

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Boltzmann equation for entropy

S = k ln(W)

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accessible microstates

probable number of arrangements of particles at a particular T

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third law of thermodynamics

entropy of a pure, perfect crystal is zero at O K

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standard molar entropy

entropy of one mole of a substance at P= 1 barr and T=25 C

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which phase of matter has the greatest entropy

gases

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quantum theory of entropy

energy levels for gas motion get closer together when the volume expands, more energy levels become accessible at a given T, E will disperse more over these levels

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when a processes product favored?

when energy is dispersed from few to many levels

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Carnot entropy equation

S= Sf-Si = qrev/T

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reversible process

can be reversed by a slight change in condition

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entropy of solids

very small as particles are essentially fixed

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entropy of liquids

moderate entropy as particles slide past eachother

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entropy of gases

large entropy as particles move freely

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Factors that increase entropy

-greater motion -greater complexity -weaker ionic force -large matter dispersal -particle mass -temperature -dissolution

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entropy of aqueous solutions

tends to be large as it allows for a greater dispersion of ions

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less condensed phase is always...

more favorable

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spontaneous process

-occurs naturally under certain conditions -can be instantaneous or slow

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nonspontaneous process

driven by a continual input of energy from an external source

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thermodynamics

study of relationships between the energy and work associated with chemical and physical properties

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spontaneous processes often result in...

greater dispersal of energy or matter

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microstates

special configuration of all the locations and energies of the atoms or molecules in a system

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increase of microstates with number of particles

exponential

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second law of thermodynamics

all spontaneous changes cause an increase in the entropy of the universe

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second law of thermodynamics equation

deltaSuniv = deltaSsys + deltaSsurr

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standard entropy change

the total entropy of the products - the total entropy of the reactants

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the total entropy of the universe is continuously...

increasing

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