Unit 1 (ch 6,10,11) Flashcards
Characteristics of gas phase
- no defined shape or volume
- compressible
- change volume with temp
- miscible
- less dense
Atmospheric pressure
1 ATM=
P ATM = force/area
1 ATM= 760 mmhg
1 ATM = how many pascals
101,325
What happens if area decreases?
Pressure increases
Boyles law
Related to pressure and volume
P = 1/V
PV= constant
P1V1=P2V2
pressure increases, volume decreases
Charles law
Related to volume and temperature
V=T
V1/T1= V2/T2
*volume increases, temperature increases
Avogadro’s law
Related to volume and number of moles
V1/n1= V2/n2
*as volume increases, number of moles increases
Amontons law
Related to pressure and temperature
P1/T1 = P2/T2
as pressure increases, temperature increases
Ideal gas law
PV=nRT
P1V1/n1T1 = P2V2/n2T2
Standard temp
0 degrees C
Standard pressure
1 bar/1atm
Standard volume
22.4 L/mol
Does gas have a greater density or less density than other forms of matter?
less
at STP density =
molar mass/molar volume
density in relation to PV=nRT
PM/RT = m/v = d (M= molar mass, m = mass)
Given that density of gases depends on their molar mass, which is the least dense?
Cl2, He, H2, N2
H2- least molar mass
highest molecular weight = most or least dense?
most
increase temperature, density (blank)
decreases
decrease temperature, density (blank)
increases
Dalton’s law of partial pressures
Ptot = P1 + P2 + P3…
mole fraction
moles of one element/total moles of all elements
Partial pressure of a gas =
mole fraction x Ptotal
Kinetic molecular theory of gases list
1) gas molecules are tiny compared to the volume they occupy
2) move constantly and randomly
3) motion associated with average KE (same temp= same KE)
4) collisions with other molecules and walls of container are elastic (T and V constant)
5) assume no attraction or repulsion between gas molecules
with gases, smaller V means (blank) collisions and (blank) pressure
increase, increase
More molecules means (blank) collisions and (blank) pressure
increase, increase
Higher temperature means (blank) collisions and (blank) pressure
increase, increase
Molecular speed and kinetic energy
KE = 1/2 mu^2
Three important values
- Um
- Uavg
- Urms
(most common speed)
(average speed)
(root mean square speed)
larger gas moves faster or slower?
slower
KE avg is the same for different gases at the same (blank)
temperature
Graham’s law is related to
effusion and diffusion
Van der Waal’s equation
(P + n^2a/v^2) x (v-nb) = nRT
solids have (blank) interparticle forces KE (blank) attraction
strong,
liquids have (blank) interparticle forces KE (blank) attraction
medium, >
gases have (blank) interparticle forces KE (blank) attraction
weak,»_space;
strong forces = solid with (blank) boiling point
high
weak forces = gas with (blank) boiling point
low
ion-ion interactions
ionic compounds
strongest
E = (blank)/(blank)
E = (Q1Q2)/d (smaller distance = stronger)
stronger interactions with (blank) distance
smaller
Interactions between polar molecules include and they relate to differences in (blank)
ELECTRONEGATIVITY
- ion-diple
- diploe-diple
- —hydrogen
ion-dipole interactions
ions and polarized molecules
ex) water and salt
Dipole-Dipole
weaker, less organized
Hydrogen
special type of dipole-dipole
O-H, N-H, or F-H
H bonded to highly electronegative element
increase boiling point
Dispersion forces
london dispersion, induced-dipole induced dipole
occur between all molecules
weakest
change in electron distribution
larger molecules = more force (more polarized)
Which is the most polarizable? I2, Br2, Cl2, F2
I2
Why do strenghts of London forces increase with size?
larger molecules have more electrons and therefore, more distortions and a bigger force
-nonpolar liquid (oil)= high boiling
Van der Waals forces
non-ideal gases
(P + n^2a/v^2)(v-nb)=nRT
Thinking about the factors that influence Van der Waals constants, which do you expect to have the larges a constant? He, H2O, N2, NO
H2O
key point with polarity and solubility
LIKE DISSOLVES LIKE
O2 has (blank) solubility in H2O
limited
increase temp, (blank) gas solubility
decrease
fish example
O2 less soluble with heat, fish die in warm water
low pressure (high elevation) = (blank) gas solubility
lower
Henry’s law
Cgas= KH-Pgas
concentration, constant, partial pressure
hydrophobic vs hydrophillic
fearing vs loving
what two things influence the phase of matter?
temperature and pressure
solid CO2 =
dry ice
qualities of water
higher melting and boiling point
forms strong H-bonds
surface tension
cohesive forces
molecules sticking together
adhesive forces
molecules sticking to other things
stronger forces = (blank) viscous
more
pentane vs car oil- which is more viscous
car oil
What is more viscous, freshwater or seawater?
seawater
cold water = (blank) dense
most
solvent dissolves (blank)
solute
breaking bonds example
NaCl (ionic)
making bonds example
NaCl in H2O (ion-dipole)
delta H solution =
delta H ion-ion + delta H dipole-dipole + delta H ion-dipole
delta H solution = break + make
delta H ion-ion (break) + delta H hydration (make)
lattice energy
U = K (Q1Q2)/d
-more negative U is harder to dissolve
lattice energy trend
smaller ion (top right)= larger negative energy
which has a higher lattice energy RbF or LiF?
LiF
Born-Haber cycle
series of chemical steps to make ionic solid from elements
delta H solution = delta H hydration (+ or -? U)
-
rate of vaporization depends on
pressure, temp, surface area, strength of intermolecular forces
temperature increases, vapor pressure (blank)
increases
delta H hydration for H2O is positive or negative?
negative
in general, if solute is nonvolatile, vapor pressure (blank)
decreases
nonvolatile examples
sugar and salt
Which of the following would not lower the vapor pressure of H2O?
- Acetic acid (118.1 C)
- Ethylene glycol (197)
- Glycerol (290)
- Methanol (64.5)
methanol
Raoult’s law
Psolution= mole fraction solvent x P solvent
clausius-clapeyron equation
ln (Pvap T1/Pvap T2) = delta H vap/ R (1/T2 -1/T1)
vapor pressures of mixtures equation
Ptotal=mole fraction x vapor pressure + (same)
Colligative properties of solutions
- freezing point depression
- boiling point elevation
- density increase
- osmosis and osmotic pressure
molality
nsolute/kg solvent
boiling point elevation
delta Tb=kb x m
freezing point elevation
delta Tf = kf x m
van’t hoff factor (i)
nonelectrolytes vs electrolytes
solvent moves from (blank) solute to (blank)
low to high
Osmotic pressure equation
pi= i x M (moles/L) x R x T (kelvin)
ethylene glycol in water is
antifreeze
What differentiates gases from the other phases?
no shape/volume, compressible, miscible, less dense
Patm=
F/A
What are the gas laws?
Boyles (P and V)
Charles (V and T)
Avogadros (V and n)
Amontons (P and T)
Ideal gas law
PV = nRT
standard conditions for the ideal gas law
0 degrees C and 1 atm/bar
1 mol ideal gas = blank L
22.4
gases in reactions compare (blank)
V and P
gas density
less dense than other faces
d= molar mass/molar volume
density =
P x molar mass/ RT
As temperature increases, density (blank)
decreases
how can we use density to determine molar mass?
molar mass = dRT/P
Dalton’s law
each gas in a mixture has a partial pressure
Ptotal= sum of partial pressures (P1 + P2 + P3)
moles of gas
ntotal= n1+n2…
mole fraction Xx
nx/ntotal (moles of the component/ total moles)
Partial pressure =
mole fraction x total pressure (Px = (Xx)(Ptotal)
For any given mixture, the sum of the mole fractions =
1
Kinetic molecular theory of gases
- gas molecules tiny compared to volume they occupy
- move constantly and randomly
- motion associated with average kinetic energy
- collisions are elastic
- no attraction between molecules
collisions are what generates (blank)
pressure
smaller volume = (blank) collisions
more
smaller volume = (blank) pressure
increase
more molecules = (blank) collisions = (blank) pressure
more, increased
KE equation
1/2 m u^2 (m= mass, u = speed)
um= most common speed
uavg= average speed
urms= root mean squared speed
urms
speed of particle with KEavg
sqrt(3RT/molar mass)
KEavg
1/2 m (urms)^2
heavier molar mass = (blank) speed
slower
Graham’s law
gases move from high pressure to low pressure
rate is inversely proportional to the (blank)
square root of molar masses
r1/r2 = sqrt (molar mass2/molar mass1)
Van der waal’s equation
(P + n^2a/v^2)(v-nb) = nRT
solid- KE (blank) intermolecular attraction
liquid- KE (blank) intermolecular attraction
>
gas- KE (blank) intermolecular attraction
> >
strong forces and high melting = solid, liquid, or gas?
solid
strength of interparticle/intermolecular intereactions influences (blank)
phase, melting, and boiling points
weak forces and low boiling = solid, liquid, or gas
gas
types of interactions
ion-ion (E Q1Q2/d) ion-dipole dipole-dipole hydrogen dispersion forces
dispersion forces explained
nonpolar molecules form temporary or induced dipoles
induced dipole is the (blank)
temporary shift in the electron distribution around the atoms/bonds
(blank) can influence the strength of dispersion forces
shape
what molecules stack well and what don’t?
linear, spherical
How can dispersion forces become strong?
added together
Van der Waal’s forces
nonideal gases interact
Intermolecular forces also explain
solubility
If we mix H2O and MeOH, they both have what type of force? What does this mean?
dipole-dipole/hydrogen bonds
they can form new dipole-dipole interactions with each other, increase solubility
If we mix H2O with octane, what forces are present? What does this mean?
dispersion, you have to break the hydrogen bonds and dispersion forces but only left with dispersion in end= unfavorable
Gas solubility in H2O - increased T =
decreased solubility (gases gain more KE, escape solvent)
Solubility in H2O depends on
gas partial pressure- Henry’s law
What molecules form cell membranes?
molecules that interact through multiple types of forces
- polar and non polar ends
cell membranes are also known as
phosopholipids
What do phase diagrams do?
tell us what phases should be present at a given T and P and where transitions between the phases should occur
supercritical region
a region where a compound behaves as sort of a gas-liquid hybrid
Why is water amazing?
strong hydrogen bonds
Solutes affect solution properties such as
melting point, boiling point, and vapor pressure
When we dissolve a solute in a solvent, we are doing what?
breaking some bonds and forming new ones
Delta H solution =
delta H hydration - U (lattice energy)
lattice energy =
k(Q1Q2)/d
Born Haber cycle
breaking a complicated chemical reaction into its basic steps and analyzing the energy for each of those steps
delta H hydration (NaCl) can be broken into
delta H hydration Na = delta H hydration Cl
Vapor pressure
the pressure exerted by a gas above a liquid in a closed system when equilibrium between evaporation and condensation is reached
Vapor pressure can tell us (blank) and increases with (blank)
fast; temp
If we dissolve a nonvolatile solute, vapor pressure
drops
vapor pressure of pure water is (blank) seawater
greater than
Raoult’s law
Psolution = Xsolvent x Psolvent (mole fraction x vapor pressure of solvent)
mole fraction is the
ratio of moles of one component of a mixture to the entire mixture (nx/ntotal)
Colligative properties
depend on concentration of solute
Mixtures of volatile solutes can be found using what equation?
clausius-clapeyron
Clausius- Clapeyron
ln(PvapT1/PvapT2) = delta Hvap/R(1/T2-1/T1)
In a volatile mixture, Ptotal =
X1P1 + X2P2
Colligative properties
molality, boiling point elevation, freezing point depression, osmosis
molality
nsolute/kg solvent
boiling point elevation
delta Tb = kb x m (i)
freezing point depression
delta Tf = kf x m (i)
Van’t Hoff factor is needed to account for
when dissolved, not all 1 m solutions have the same number of “particles”
Van’t Hoff factor = i =
number of “particles” we get when we dissolve a compound
NaCl i =
2
CaCl2 i =
3
glucose i =
1
at higher concentrations of solute we see (blank)
ion pairing, vh decreases
Osmosis
movement of solvent through a semipermeable membrane from an area of low solute concentration to high solute concentration
osmotic pressure
pi = iMRT
Osmotic pressure is super important in
IV administration and reverse osmosis
Explain why the boiling point of Br2 (59C) is lower than that of iodine monochloride, ICl (97C), even though they have nearly the same molar mass.
ICl is polar while Br2 is no polar.
Polar liquids have higher or lower boiling point?
Higher, dipole dipole
In an aqueous solution containing Sn (II) and Sn (IV) salts, which cation would you expect to be the more strongly hydrated? Why?
Sn4+ because it is a smaller ion with a larger charge.
Which of the following compounds is expected to have the weakest interactions between its molecules? CO2, NO2, SO2, H2S
CO2
Which of the following compounds is expected to have the strongest interactions between its molecules? CO2, NO2, SO2, H2S
SO2
Why do the strengths of London dispersion forces generally increase with increasing molecular size?
Dispersion forces arise from dipoles caused by the electron distribution being distorted. Larger molecules have more electrons and therefore, more distractions and a bigger force.
What substances are insoluble in water? KBr (s), Benzene, C6H6 (l), Br2(l)
Benzene and Br2
Smaller ions of the same charge form compounds that are (blank) soluble than compounds from larger ions.
Less
Ions with higher charges form compounds that are (blank) soluble than ions of a lower charge.
Less
Rank the following compounds in order of increasing solubility in water.
CaO, BaO, KCl, KI
The most soluble compounds in water is th compound with the (blank) hydrophobic hydrocarbon chain.
Shortest
Solid helium cannot be converted directly into the vapor phase. Does the phase diagram of He have a triple point?
No, without a sublimation curve there can be no triple point.
What kind of intermolecular forces must be overcome during a the phase change in which solid CO2 sublimes?
Dispersion
What kind of intermolecular forces must be overcome during a the phase change in which CHCl3 boils?
Dispersion
Dipole-dipole
What kind of intermolecular forces must be overcome during a the phase change in which ice melts?
Dispersion, dipole-dipole, hydrogen
At 1 ATM and 0 C, water is
Solid and liquid
A hot needle sinks when out on the surface of cold water. Will a cold needle float or sink in warm water?
The hot needle breaks the surface tension of the water, causing it to sink. A cold needle cannot break up the surface tension of the water, so it floats.
Does hot water have a higher or lower surface tension than cold water?
Lower
Explain why different liquids do not reach the same height in capillary tubes of the same diameter.
Cohesive forces stronger than adhesive forces reduce the height of the liquid in the capillary tube, whereas adhesive forces stronger than cohesive forces increase the height of the liquid.
The smaller the diameter of a tube, the (blank) the liquid rises up the tube by capillary action.
Higher
Water has higher surface tension and viscosity than
Methanol
What makes a substance soluble in water?
Polar and can form hydrogen bonds with water molecules.
Of the following compounds, LiF- NaCl- or KI, which should have the highest melting point?
LiF
The smallest distance between the ions and highest charges =
Higher lattice energy and melting point
When the vapor pressure of a liquid is equal or greater than atmospheric pressure, the liquid will (blank)
Boil
The higher the vapor pressure of a given liquid, the (blank) the boiling point.
Lower
As the size of atomic number increases, the Latrice energy and melting point (blank)
Decrease
Vapor pressure depends on (blank)
Temperature
The higher the temperature, the (blank) the vapor pressure.
Higher
The higher the molarity of the, the (blank) the osmotic pressure.
Higher
