Exam One Flashcards
As the molecules of a gas attract each other into a liquid and then become fixed in a solid, the system is […] energy. This is an […] change.
loses; exothermic
Overcome the attractive forces that keep the particles fixed in place in a solid or near each other in a liquid. The system must […] energy. This is an […] change.
absorbs; endothermic
Melting or […]. The enthalpy change is […]. For freezing the enthalpy change is […].
fusion; positive; negative
Gas formation or […]. The enthalpy change is […]. For condensation, the enthalpy change is […].
vaporization; positive; negative
Sublimation:
solid goes to a gas
Sublimation calculation of enthalpy change:
heats of fusion + heats of vaporization
Deposition:
gas goes to solid
Deposition calculation of enthalpy change:
(-) heats of fusion + (-) heats of vaporization
Molecules with weaker IMF are held […] tightly at the surface and vaporize more […]. Weaker IMFs are, the […] the vapor pressure.
less; easily; higher
Vapor pressure and temperature can be converted to a linear relationship with the use of…
Clausius-Clapeyron
Clausius-Clapeyron Equation at one at two known temperatures:
lnP = (-Hvap/R) (1/T) + C
ln(P2/P1) = (-Hvap/R) (1/T2-1/T1)
R = 8.314 J/mol*K
% By Mass Equation:
mass of solute/ mass of solution
% By Volume Equation:
volume of solute/ volume of solution
Molality Equation:
amount of solute/ mass of solvent (kg)
Molarity Equation:
amount of solute/ volume of solution
Mole Fraction:
amount (mole of solute)/ amount of solution (mole solute + mole of solvent)
Regions of the phase diagram represent…
conditions of pressure and temperature at which the phase is stable
Solid-liquid line has a slightly positive slope because…
the solid is more dense than the liquid (except water)
The triple pint of a phase diagram where…
all three phases are in equilibrium (simultaneous work)
Critical point:
two densities become equal and the phase boundary disappears
How does the phase diagram for water differ?
the solid-liquid line has a negative slop because the solid form is less dense
How does the phase diagram for water differ?
the solid-liquid line has a negative slop because the solid form is less dense
List the 3 bonding forces:
ionic
covalent
metallic
List the 6 IMF forces:
ion-dipole (NaH2O)
H-bond (H to N, O, F)
ion-induced dipole (FeO2)
dipole-dipole (ICl-ICl)
dipole-induced dipole (HCl-ClCl)
dispersion (F2-F2)
Ion-Dipole forces: The prime example would be…
Why does this occur?
any ionic compound dissolving in water
the attraction between the negative pole and ion is greater than the between the ions themselves
If the dipole-dipole forces of 2 compounds have a similar mass, what can determine the stronger force?
the one with the greater dipole moment
For a NP molecule, distortion of an electron cloud induces a […].
temporary dipole moment
For a P molecule, distortion of an electron cloud induces an […].
increase in the already existing dipole moment
Polarizability:
how easily the electron cloud of an atom can be distorted
Which is more polarizable: smaller particles or larger ones?
larger; smaller molecules are held more closely to the nucleus
List the 2 trends of the PT when it comes to polarizability:
- increases down a group (atomic size increases and larger electron clouds are easier to distort)
- decreases across a period (increasing Zeff makes the atoms smaller and hold the electrons more tightly)
Cations are […] polarizable than their parent atoms because they are smaller. Anions are […] polarizable because they are larger.
less; more
When an ion distorts the electron cloud of a NP substance what forces result?
an ion-induced dipole
When a P molecule causes the distortion to an NP electron cloud what forces result?
a dipole-induced dipole
London dispersion occurs between all particles because they result from…
the motion of electrons
Dispersions are also known as…
instantaneous dipole-induced dipole forces
How can a dipole be formed in a dispersion electron cloud?
instantaneously there’s more electrons on one side of the nucleus than the other
The relative strength of dispersion forces depends on the […] of the particles.
polarizability
A linear chain of carbons vs a tetrahedral shape. If the two have equal mass which has the higher bp?
chain because there are more points at which dispersion forces act
IMF: Ion + P =
ion-dipole forces
IMF: Ion + NP =
ion-induced dipole forces
IMF: P + NP =
dipole-induced dipole forces
IMF: P + P =
dipole -dipole forces
How to determine which compound has the highest vapor pressure?
Why is this the case?
the one with the strongest IMF has the lower vapor pressure
substances with stronger IMF mean fewer molecules will have enough kinetic energy to escape at a given temperature
We can divide solids into two broad categories:
- crystalline
2. amorphous
Crystalline solids:
well defined shapes because their particles occur in an orderly arrangement
Amorphous solids:
poorly defined shapes because of the lack of orderly arrangement
Unit cell:
the smallest portion of a crystal that, if repeated in all three directions, yields the crystal
Coordination number:
in a crystal, the number of nearest neighbors surrounding a particle
in a complex ion, the number of ligand atoms bonded to the central metal ion
List the three types of cubic cell units:
- simple
- body centered
- face centered
The coordination of each cubic cell unit:
6 for simple
8 for body-centered
12 for face-centered
How many particles make up a simple cubic? Explain with the formula.
1
(8 corners) x (1/8 particle shared between adj cells) = 1
How many particles make up a body-centered cubic? Explain with the formula.
2
(8 corners) x (1/8 particle shared between adj cells) = 1 + 1 particle in the center = 2
How many particles make up a face-centered cubic? Explain with the formula.
4
(8 corners) x (1/8 particle shared between adj cells) = 1 + (1/2 particle shared at the face) x (6 faces) = 4
Atomic solids/ noble gases crystallize in a […].
cubic closest packing (face-centered cubic unit cell)
Molecular solids have molecules at the lattice points and often adopt […].
cubic closest packing
Ionic solids crystallize with one ion filling hold in the […] array of the other.
cubic closest packing
Most metals have a […].
closest packed structure
What are some examples of amorphous solids?
charcoal, rubber, glass
Why can’t amorphous solids remain ordered?
the chains of atoms cannot orient themselves quickly enough so they solidify in a distorted jumble of misaligned rows and gaps
Atomic physical properties (3)
- soft
- very low mp
- poor conductor
Substances with strong IMF have a […] vapor pressure and are less […].
lower; volatile
Molecular physical properties (3):
- fairly soft
- low-mod mp
- poor conductor
Ionic physical properties (3):
- hard and brittle
- high mp
- good conductor (molten)
Metallic physical properties (3):
- soft to hard
- low-high mp
- excellent conductor
Network covalent physical properties (3):
- very hard
- very high mp
- poor conductor
Examples of hexagonal packing:
Mg, Ti, Zn
Example of cubic closest:
Ni, Cu, Pb, CO2, CH4, noble gases
Solvent:
substance in which other substances dissolve; the most abundant component
Solute:
substance that dissolves in a solvent
Solubility:
maximum amount that dissolves in a fixed quantity of a given solvent at a given temperature
Miscible:
soluble at any proportion
Liquids that do not dissolve each other are […].
immiscible
Solubility of alcohols in water: when is it too low that the mixture is insoluble?
when alcohols larger than three carbons solubility decreases; insoluble at 6 or more
What is polar?
the uneven distribution of electron density
What does it mean to be polar?
to have a separation of charge leading to a molecule or compound electrical dipole moments
