chem test 3

Question 1

boyle’s law

Answer 1

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

Question 2

charles law

Answer 2

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

Question 3

combined gas law

Answer 3

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

Question 4

avogadro’s hypothesis

Answer 4

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

Question 5

ideal gas law

Answer 5

PV=nRT

Question 6

R

Answer 6

.08206 Latm/Kmol

8.314 J/Kmol

Question 7

daltons law

Answer 7

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

Question 8

mole fraction

Answer 8

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

Question 9

kinetic molecular theory of gases

Answer 9

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

Question 10

root mean square velocity (average velocity)

Answer 10

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

Question 11

grahams law

Answer 11

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

Question 12

two reasons that real gases not ideal

Answer 12

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

Question 13

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

Answer 13

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

Question 14

kinetic energy

Answer 14

energy due to motion

Question 15

potential energy

Answer 15

energy due to position

Question 16

thermal energy

Answer 16

energy due to temperature

Question 17

first law of thermodynamics

Answer 17

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

Question 18

two kinds of heat

Answer 18

latent and change in temp

Question 19

change in temp equation

Answer 19

q=mCΔT

Question 20

exothermic

Answer 20

heat given off, ΔH

Question 21

endothermic

Answer 21

heat is absorbed, ΔH>0

Question 22

equation for work

Answer 22

w= -PΔV

Question 23

enthalpy

Answer 23

heat involved in constant pressure process

Question 24

ΔH

Answer 24

symbol for change in enthalpy

Question 25

calorimeter

Answer 25

device used to measure heat

Question 26

says enthalpies of reaction are additive

Answer 26

Hess’

Question 27

ΔH^o f

Answer 27

symbol for standard enthalpy of formation

Question 28

significance of ΔH

Answer 28

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

Question 29

Hess’ law

Answer 29

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

Question 30

ΔH^o

Answer 30

standard=1 atm pressure and 25oC

Question 31

standard enthalpy of formation

Answer 31

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

Question 32

bond energy

Answer 32

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

Question 33

bomb calorimeter

Answer 33

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

Question 34

coffee cup calorimeter

Answer 34

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

Question 35

spontaneous change

Answer 35

change that takes place without the need to provide heat

Question 36

thermodynamics

Answer 36

scientific study of heat, work, and energy

Question 37

second law of thermodynamics

Answer 37

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

Question 38

entropy

Answer 38

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

Question 39

ΔS=ΔH/T

Answer 39

formula for ΔS

Question 40

ΔSo

Answer 40

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

Question 41

So

Answer 41

absolute entropy of a substance

NEVER A CHANGE

Question 42

third law of thermodynamics

Answer 42

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

Question 43

absolute entropies determined

Answer 43

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

Question 44

another name for absolute entropies

Answer 44

third law entropies

Question 45

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

Answer 45

enthalpy goes down (decreases,

Question 46

reaction is more likely to occur if the entropy does what

Answer 46

goes up (increases, >0, endothermic)

Question 47

Gibbs Free energy

Answer 47

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

Question 48

driving force for spontaneity

Answer 48

what makes delta G

Question 49

ΔGof

Answer 49

standard Gibbs free energy of formation

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