Chem Exam 3

Front 1

Atomic orbitals on different atoms combine to form ___.

Back 1

molecular orbitals

Front 2

___ in molecular orbitals belong to molecule as a whole.

Back 2

Electrons

Front 3

Molecular bonding theory is another bonding theory, separate from ____.

Back 3

localized electron theory.

Front 4

MO theory allows more accurate predictions of :

Back 4

magnetic properties
bonding

Front 5

2 main results of interfering wavefunctions:

Back 5

constructive and destructive

Front 6

Greater bond order we predict:

Back 6

more stable molecule.
short bond length.
higher bond energy.
multiple bonds have higher bond energy.

Front 7

Atomic orbitals of different elements have same/similar Aufbau order but have different ___ due to a difference in ____.

Back 7

energies
electronegativity

Front 8

Molecules very far apart:
Molecules close together:

Back 8

gases
liquids, solids

Front 9

Properties of gases:

Back 9

-expands to fit available volume(creates a force on ALL sides of vessel described by a pressure measurement)
-compresible
-Volume and pressure vary greatly with temperature.

Front 10

Variables that influence a gas sample:

Back 10

Pressure, Temperature, Volume, Moles

Front 11

Pressure exerted by Earth's atomosphere on a give day in a given location:

Back 11

Atmospheric pressure

Front 12

Force per unit area:

Back 12

pressure

Front 13

Standard atmospheric pressure is:

Back 13

760 mm Hg
760 torr
1 atm
101.325 kPa
1.01325 bar

Front 14

n

Back 14

number of moles

Front 15

Gas exerts pressure due to molecule collisions with container walls.

Back 15

Boyle's Law. Pressure/Volume Relationship

Front 16

P1V1=P2V2

Back 16

Boyle's Law

Front 17

Pressure and volume are ___ proportional.

Back 17

inversely

Front 18

V1/T1=V2/T2
V is directly proportional to the absolute temperature.

Back 18

Charles's Laws

Front 19

STP=

Back 19

0 degrees Celcius
1 atm

Front 20

Avogadro's Law

Back 20

V1/n1=V2/n2
constant T, P
Equal volumes of gases(at same T, P) contain the same number of molecules.

Front 21

ideal gas law:

Back 21

PV=nRT
R=universal gas constant=.0821

Front 22

Total pressure equation:

Back 22

Ptotal=Pa+Pb+Pc+..

Front 23

Dalton's Law of Partial Pressures:

Back 23

Pa=Xa*Ptotal

Front 24

Dalton's Law of Partial Pressures:

Back 24

Total pressure exerted by a mixture is sum of partial pressures of the gases in the mixture.

Front 25

mole fraction:

Back 25

Xa=# of moles of "a"/total # of moles

Front 26

Pa stands for:

Back 26

partial pressure

Front 27

partial pressure equation:

Back 27

Pa=naRT/V

Front 28

Kinetic Molecular Theory
For an ideal gas:

Back 28

1. gases are very small discrete molecules, spaced very far apart.
2. The molecules are in constant, random, straight-line motion until they hit another molecule of the vessel wall.
3. Any collision if perfectly elastic; no energy is lost or gained.
4. between collisions, molecules exert no attractive or repulsive forces on one another and they travel at constant speed(individual molecules move at different speeds)

Front 29

Diffusion is the ___ of gases.

Back 29

intermingling

Front 30

Effusions is the ____ of gases through tiny holes.

Back 30

escape

Front 31

Average Kinetic energy K.E. of gas particles is ____ proportional to absolute temperature of the gas.

Back 31

directly

Front 32

Non-ideal behavior in gases generally occurs at

Back 32

high pressures, low temperatures

Front 33

Real gases at high pressure:

Back 33

-gas compressed
-Volume of molecules is significant fraction of container volume.
-Correction factor: nb
n=moles
b=dependent on size of molecules
- V avaliable=Vmeasured-nb

Front 34

Real gases at low temperatures:

Back 34

-molecules moving slowly
-Attractive forces between molecules become important
even more important at small V(molecules closer together)
-Collisions with wall less often, less energetic
-Correction factor: n^2a/V^2

Front 35

Forces that hold together an individual molecule

Back 35

Intramolecular forces

Front 36

forces between different molecules:

Back 36

Intermolecular forces

Front 37

Intermolecular forces are based on attraction of _____.

Back 37

opposite charges

Front 38

In covalent molecules, intermolecular forces are based on the _____.

Back 38

molecule polarity

Front 39

A molecule which is polar overall will have a __.

Back 39

net dipole

Front 40

Forces between polar molecules:

Back 40

dipoles

Front 41

Dipole-Dipole interactions have only 1% the strength of a ____ bond.

Back 41

covalent

Front 42

In dipole-dipole interactions, the positive end of one attracts negative end of the other(dipoles line up to maximize attraction; minimize repulsion)
t/f?

Back 42

True

Front 43

Hydrogen bonds are highly ____.

Back 43

polarized

Front 44

A hydrogen bond is just a very strong ______.

Back 44

dipole-dipole interaction.

Front 45

Are the weakest type of force:

Back 45

London Forces/dispersion forces

Front 46

London forces assume existence of temporary (instantaneous) ___.

Back 46

dipoles

Front 47

_____ forces exist in ALL molecules but are the ONLY form of interaction in nonpolar molecules.

Back 47

London Forces

Front 48

Stronger Intermolecular interactions means:

Back 48

it is HARDER to separate the component atoms/ions.
means HIGHER melting and boiling points.