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Chemistry 111 > chem test 3 > Flashcards

chem test 3 Flashcards

1
Q

boyle’s law

A

volume of a gas is inversely proportional to its pressure at a constant temperature, PV=const T

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2
Q

charles law

A

volume of a gas is directly proportional to its temperature at constant pressure, V/T=const P

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3
Q

combined gas law

A

PV/T=const at const # moles, P1V1/T1=P2V2/T2

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4
Q

avogadro’s hypothesis

A

equal volume of gases at the same temperature and pressure will have an equal number of moles and molecules

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5
Q

ideal gas law

A

PV=nRT

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6
Q

R

A

.08206 Latm/Kmol

8.314 J/Kmol

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7
Q

daltons law

A

partial pressures, total pressure for a mixture of gases is the sum of the partial pressure of each gas, P=ΣPi

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8
Q

mole fraction

A

moles of i/total moles=mole fraction xi
no unites
sum =1

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9
Q

kinetic molecular theory of gases

A

gases made up of very small molecules
molecules are in continuous random motion
average kinetic energy is 1/2Mv^2=32RT
collisions with the walls and other molecules are perfectly elastic

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10
Q

root mean square velocity (average velocity)

A

U(rms)=[3RT/M]^(1/2)

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11
Q

grahams law

A 
of effusion (no room for molecule to come in while another one leaves)
rate of effusion of a gas is inversely proportional to the square root of the molecular weight of the gas
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12
Q

two reasons that real gases not ideal

A

real gases have attractions between the molecules, so collisions are not perfectly elastic
real gas molecules are small, but not infinitely small, they have volume

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13
Q

(P+n^2+a/v^2)(V-nb)=nRT

A

van der Waals equation
a is a measure of the attractive forces between the gas molecules
b is a measure of the size of the gas molecules

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14
Q

kinetic energy

A

energy due to motion

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15
Q

potential energy

A

energy due to position

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16
Q

thermal energy

A

energy due to temperature

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17
Q

first law of thermodynamics

A

energy can neither be created nor destroyed, ΔE=q+w

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18
Q

two kinds of heat

A

latent and change in temp

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19
Q

change in temp equation

A

q=mCΔT

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20
Q

exothermic

A

heat given off, ΔH

21
Q

endothermic

A

heat is absorbed, ΔH>0

22
Q

equation for work

A

w= -PΔV

23
Q

enthalpy

A

heat involved in constant pressure process

24
Q

ΔH

A

symbol for change in enthalpy

25
Q

calorimeter

A

device used to measure heat

26
Q

says enthalpies of reaction are additive

A

Hess’

27
Q

ΔH^o f

A

symbol for standard enthalpy of formation

28
Q

significance of ΔH

A

heat involved in a constant pressure process, and chemists do a lot of things at constant pressure

29
Q

Hess’ law

A

law of constant heat summation, add up delta H’s

30
Q

ΔH^o

A

standard=1 atm pressure and 25oC

31
Q

standard enthalpy of formation

A

ΔH^o f, delta h for the formation of 1 mole of the substance from its elements in their standard state at 1 atm and 25oC, products-reactants

32
Q

bond energy

A

average energy required to break a particular bond in the gas phase

33
Q

bomb calorimeter

A

piece of equipment that is used to fine experimental values of standard enthalpies of combustion, by burning sample in high oxygen concentration all delta Hoc values are negative

34
Q

coffee cup calorimeter

A

coffee cup calorimeter is a device used to measure delta Ho for reactions in solution

35
Q

spontaneous change

A

change that takes place without the need to provide heat

36
Q

thermodynamics

A

scientific study of heat, work, and energy

37
Q

second law of thermodynamics

A

entropy of the universe for aspontaneous change always increases
ΩS(universe)>0

38
Q

entropy

A

S is a measure of the randomness of the system
S=klnΩ (omega ways to arrange the system)
k=boltzmann’s constant=R/Na=1.38x10^-23 J/K

39
Q

ΔS=ΔH/T

A

formula for ΔS

40
Q

ΔSo

A

change in the entropy (products-reactants) for a reaction at a standard state

41
Q

So

A

absolute entropy of a substance

NEVER A CHANGE

42
Q

third law of thermodynamics

A

entropy of any perfectly cystalline substance at absolute 0K is zero
So0=0
So(0)=0

43
Q

absolute entropies determined

A

So298=So0 + integral 0 to 298 C/T dt

44
Q

another name for absolute entropies

A

third law entropies

45
Q

reaction is more likely to occur if the energy (enthalpy) does what

A

enthalpy goes down (decreases,

46
Q

reaction is more likely to occur if the entropy does what

A

goes up (increases, >0, endothermic)

47
Q

Gibbs Free energy

A

combination of enthalpy and entropy, J or kJ/mol
ΔG=ΔH-TΔS
if delta G is negative, the reaction is spontaneous

48
Q

driving force for spontaneity

A

what makes delta G

49
Q

ΔGof

A

standard Gibbs free energy of formation

delta Go for the reaction forming 1 mole of the substance from its elements in their standard states

Chemistry 111 (7 decks)

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