question

Dispersion Forces

answer

Random electron motion produces an unbalanced charge distribution producing a temporary dipole

question

Halogens

answer

Fluorine
chlorine
bromine
iodine

question

dispersion forces occur for

answer

all particles

question

the relative strength of dispersion forces depend on

answer

the polarizability of the particle

question

polarizability depends on

answer

the number of electrons and the shape of the particles

question

the total number of energy levels produced equals the

answer

total number of orbitals used

question

the hydrogen bond is a special case of

answer

dipole dipole interaction

question

DNA is an example of ____ bonding

answer

hydrogen

question

a solution is a ______ mixture

answer

homogeneous

question

the solubility is the

answer

maximum amount of solute that will dissolve in a fixed quantity of solvent

question

miscible:

answer

soluble in each other in all portions

question

immiscible:

answer

not soluble in any portions

question

saturated:

answer

all it can hold

question

unsaturated:

answer

can hold more

question

supersaturated:

answer

more than it can hold

question

molarity (M) equation

answer

mol of solute / L of solution

question

molality (m) equation

answer

mol of solute / mass (kg) of solvent

question

parts by mass equation

answer

mass of solute / mass of solution

question

parts by volume equation

answer

volume of solute / volume of solution

question

mole fraction equation

answer

mol of solute / (mol of solute + mol of solvent)

question

substances with similar types of intermolecular forces ____ in each other

answer

dissolve

question

solute particles separate from each other

answer

endothermic

question

solvent particles separate from each other

answer

endothermic

question

solute and solvent particles mix

answer

exothermic

question

solvation of ions by water is always

answer

exothermic

question

the idea of energy was first developed by

answer

clausius

question

solubility of gases usually decrease with

answer

temperature

question

henry's law

answer

solubility of gases in a liquid is proportional to the pressure of the gas over the liquid

question

Boiling point elevation
DTb =

answer

Kbm

question

Freezing point depression
DTf =

answer

Kfm

question

Osmotic Pressure Equation

answer

pie = M R T
where M is the molarity,
R is the ideal gas law constant and
T is the Kelvin temperature

question

symbol of osmotic pressure is

answer

pie

question

The van’t Hoft factor, i, tells us

answer

hat the “effective”
number of ions are in the solution.

question

i =

answer

measured value for electrolyte solution/
expected value for nonelectrolyte solution

question

Four factors can be controlled during the reaction

answer

1. Concentration - molecules must collide to react;
2. Physical state - molecules must mix to collide;
3. Temperature - molecules must collide with enough energy to react;
4. The use of a catalyst.

question

reaction rate -

answer

changes in the concentrations of reactants or products per unit time

question

reactant concentrations ______ while product concentrations _____

answer

decrease; increase

question

Rate =

answer

k [A]^m [B]^n
k = rate constant
m = order of reaction in A
n = order of reaction in B
m+n = overall order of reaction

question

Collision Theory

answer

Chemical Reactions occur during collisions

question

The Collision must be effective:

answer

1. Have enough energy to produce the reaction
2. Have the correct orientation to produce the reaction

question

Transition state theory (TST) explains

answer

the reaction rates of elementary chemical reactions.
The theory assumes a special type of chemical equilibrium (quasi-equilibrium) between reactants and
activated transition state complexes

question

A complex reaction can proceed by a series of _____ ______

answer

elementary reactions

question

The rate of reaction is often determined by one slow step

answer

(rate-determining or rate- limiting step).

question

Homogeneous Catalysts

answer

They are in the same phase as the reactants (usually liquid)

question

Homogeneous Catalysts are Often

answer

acids, bases, transition metal complexes

question

Heterogeneous Catalysts

answer

Catalyst is in a different phase from the reactants (usually solid)

question

____ are considered Heterogeneous Catalysts

answer

Enzymes

question

phase

answer

each physical state

question

potential energy in the form of intermolecular forces tends to

answer

draw the molecules together

question

kinetic energy associated with the random motion of molecules tends to

answer

disperse the molecules

question

intramolecular forces exists

answer

within each molecule

question

intermolecular forces exist

answer

between each molecule

question

gas compressibility is

answer

high

question

liquid compressibility is

answer

very low

question

solid compressibility is

answer

almost none

question

gas ability to flow

answer

high

question

liquid ability to flow

answer

moderate

question

solid ability to flow

answer

almost none

question

gas to liquid

answer

condensation

question

liquid to gas

answer

vaporization

question

liquid to solid

answer

freezing

question

solid to liquid

answer

fusion or melting

question

gas to solid

answer

deposition

question

solid to gas

answer

sublimation

question

exothermic changes

answer

condensing, freezing and depositing

question

endothermic changes

answer

melting, vaporizing and subliming

question

heating cooling curve shows

answer

the change in temperature of a sample when heat is absorbed or released at a constant rate

question

symbol for heat

answer

q

question

within a phase, heat flow

answer

is accompanied by a change in temperature

question

during a phase change heat flow

answer

occurs at a constant temperature

question

liquid gas open system

answer

nonequilibrium process

question

liquid gas closed system

answer

equilibrium process

question

dynamic equilibrium

answer

the rate of condensation equals the rate of vaporization, form this point forwards the pressure is constant

question

temperature has a major effect on water vapor because

answer

it changes the fraction of molecules moving fast enough to escape the liquid and, by the same token, the fraction moving slow enough to be recaptured

question

the _____ the temperature, the ____ the vapor pressure

answer

higher; higher

question

the ______ the intermolecular forces, the _____ the vapor pressure

answer

weaker; higher

question

boiling point is

answer

the temperature at which the vapor pressure equals the external pressure

question

the boiling point depends on the

answer

applied pressure

question

melting point is

answer

the temperature at which the melting rate equals the freezing rate

question

water expands upon

answer

freezing

question

bonding forces are relatively strong because

answer

larger charges are closer together

question

intermolecular forces are relatively weak because

answer

smaller charges are farther apart

question

what force takes place when an ion dissolves in water

answer

ion dipole force

question

ion dipole force

answer

when an ion and a nearby polar molecule attract

question

dipole-dipole force

answer

the positive pole of one molecule attracts the negative pole of another

question

Hydrogen bond

answer

when an H molecule bonds with an O, N or F molecule

question

boiling points rise with

answer

increased molar mass

question

polarizability

answer

how easily the electron cloud of an atom can be distorted

question

smaller particles are _____ polarizable than larger ones

answer

less

question

polarizability increases

answer

down a group because atomic size increases

question

(larger/smaller) electron clouds are easier to distort

answer

larger

question

polarizability decreases

answer

across a period

question

Dispersion force

answer

intermolecular force responsible for the condensed states of nonpolar substances

question

dispersion forces are present in

answer

all atoms, ions and molecules because they are caused by the motion of electrons in an atom

question

an interior molecule is attracted by others

answer

on all sides

question

a surface molecule is attracted by

answer

other below and to the sides, so it experiences a net attraction downward

question

forces in CH3CH2OCH2CH2

answer

dipole-dipole and dispersion

question

forces in CH3CH2OH

answer

H bonding

question

Forces in CH3CH2CH2CH2OH

answer

H bonding and dispersion

question

Forces in H2O

answer

H bonding

question

Forces in Hg

answer

metallic bonding

question

viscosity

answer

the resistance of fluid to flow

question

viscosity decreases with

answer

heat

question

surface tension is

answer

a measure of the energy required to increase a liquid's surface area

question

capillary

answer

the rising of a liquid through a narrow space

question

viscosity depends on

answer

molecular shape

question

the great solvent power of water results from its

answer

polarity and h bonding ability

question

crystalline solids have

answer

well defined shapes because of their particles occur in an orderly arrangement

question

amorphous solids have

answer

poorly defined shapes because their particles lack an orderly arrangement

question

examples of amorphous solids

answer

rubber and glass

question

the centers of 8 identical particles define the corners of a cube

answer

simple cubic unit cell

question

the simple cubic unit cell has a coordination number of

answer

6

question

coordination number

answer

number of nearest neighbors of a particle

question

identical particles lie at each corner and at the center of the cube

answer

body centered cubic unit cell

question

the body centered cubic unit cell has a coordination number of

answer

8

question

identical particles lie at each corner and in the center of each face but not in the center of each cube

answer

face centered cubic unit cell

question

the face centered cubic unit cell has a coordination number of

answer

12

question

packing efficiency

answer

percentage of the total volume occupied by the spheres themselves

question

hexagonal unit cell has ______ _____ packing

answer

Hexagonal closet

question

face centered unit cells has ______ _____ packing

answer

cubic closest

question

atomic solids

answer

individual atoms held together only by dispersion forces

question

only substances that form atomic solids

answer

noble gases

question

inter-particle forces in atomic solids

answer

Dispersion

question

inter-particle forces in molecular solids

answer

disoersion, dipole dipole and h bonding

question

inter-particle forces in ionic solids

answer

ion ion attraction

question

inter-particle forces in metallic solids

answer

metallic bonds

question

inter-particle forces in network covalent solids

answer

covalent bonds

question

examples of network covalent solids

answer

graphite and diamond

question

electron sea model proposes

answer

that all metal atoms in a sample pool their valence electrons to form an electron sea that is delocalized throughout the piece

question

the regularity and mobility of the valence electrons in the electron sea model of metallic bonding account for three major physical properties:

answer

phase change, mechanical properties and conductivity

question

the valence and conduction bands of a conductor have _______ energy gap so

answer

no; electrons flow when a tiny electrical potential difference is applied

question

the valence and conduction bands of a semiconductor have _______ energy gap so

answer

small; thermally excited electrons can cross the gap, allowing a small current to flow

question

the valence and conduction bands of a insulator have _______ energy gap so

answer

large; no current is observed even when the substance is heated

question

mixtures

answer

two or more substances mixed together physically, not combined chemically

question

mixture has two defining characteristics:

answer

1) its composition can be variable
2) it retains some properties of its components

question

a ____ dissolves in a ____ to form a solution

answer

solute; solvent

question

ion induced dipole forces arise when

answer

an ion's charge distorts the electron cloud of a nearby nonpolar molecule

question

dipole induced forces arise when

answer

a polar molecule distorts the electron cloud of a nearby nonpolar molecule

question

intermolecular forces listed in decreasing strength

answer

ion-dipole
H bond
dipole-dipole
ion-induced dipole
dipole-induced dipole
dispersion

question

solubility in water is high for

answer

smaller alcohols

question

solubility in water is low for

answer

larger alcohols

question

solubility in hexane is low for

answer

the smallest alcohol

question

solubility in hexane is high for

answer

larger alcohols

question

gas gas solutions

answer

all gases are miscible with each other

question

gas solid solutions

answer

when a gas dissolves in a solid, it occupies the spaces between the closely packed particles

question

solid solid solutions

answer

solids diffuse so little that their mixtures are usually heterogeneous

question

alloys

answer

mixtures of substances that have a metallic character and are solid solid solutions

question

solvation

answer

the process of surrounding a solute particle with solvent particles

question

hydration

answer

solvation in water

question

change density

answer

ratio of a ion's charge to its volume

question

heats of hydrations exhibit trends based on

answer

the ion's charge density

question

entropy

answer

freedom of motion of particles

question

a _____ usually has higher entropy than the ______ solute or solvent

answer

solution; pure

question

most solids are more soluble at

answer

higher temperatures

question

the solubility of any gas in water decreases with

answer

rising temperature

question

____ has little effect on liquids and solids because

answer

pressure; the are almost incompressible

question

Henry's Law

answer

the solubility of a gas is directly proportional to the partial pressure of the gas above the solution

question

symbol for Henry's Law constant

answer

KH

question

volume percent =

answer

(volume of solute / volume of solution ) x100

question

mole percent =

answer

mole fraction x 100

question

density =

answer

mass/ volume

question

colligative properties of solutions

answer

vapor pressure lowering, boiling point elevation, freezing point depression and osmotic pressure

question

electrolyte

answer

conducts electricity

question

non electrolyte

answer

doesnt conduct electricity

question

strong electrolyte

answer

soluble salts, strong acids, strong bases
dissociate completely into ions

question

weak electrolytes

answer

weak acids and bases
dissociate very little into ions

question

Raoult's Law

answer

vapor pressure of solvent above a solution equals the mole fraction of solvent times the vapor pressure of the pure solvent

question

semipermeable membrane

answer

ones that allows solvent but not solute to pass through

question

osmosis

answer

net flow of solvent into the more concentrated solution

question

the net flow of water into a solution increases its ______ and decreases its _______

answer

volume; concentration

question

osmotic pressure

answer

pressure that must be applied to prevent net movement of water from solvent to solution

question

chemical kinetics

answer

study of how fast change occurs

question

reaction rates

answer

change in the concentrations of reactants (or products) as a function of time

question

reaction rate is proportional to

answer

concentration of reactants

question

the greater the surface area

answer

the faster the reaction occurs

question

concentration affects rate by

answer

influencing the frequency of collisions between molecules

question

physical state affects rate by

answer

determining how well reactants mix

question

temperature affects rate by

answer

influencing the frequency and the energy of the collisions

question

rate of motion (speed) =

answer

change in position / change in time

question

rate =

answer

-D[A] / Dt

question

the average rate is

answer

the slope of the line joining tow points on the curve

question

instantaneous rate

answer

rate at a particular instant during the reaction

question

initial rate

answer

instantaneous rate at the moment the reactants are mixed (at t=0)

question

the rate law expresses the rate as

answer

a function of concentrations and temperature

question

rate law equation

answer

Rate = k[A]^m[B]^n

question

symbol for rate constant

answer

k

question

three lab methods for determining the initial rate

answer

change in color
change in pressure
change in conductivity

question

the reaction is first order overall if

answer

the rate is directly proportional to [A]

question

the reaction is second order overall if

answer

the rate is directly proportional to the square of [A]

question

the reaction is the zero order overall if

answer

the rate is not dependent on [A] at all, the rate doesn't change when [A] changes

question

half life

answer

times is takes a given reactant concentration to reach half of its initial value

question

the half life of a second order reaction is

answer

inversely proportional to the initial reactant concentration

question

the half life of a zero order reaction is

answer

directly proportional to the initial reactant concentration

question

collision theory

answer

particles (atoms, molecules or ions) must collide to react

question

activation energy

answer

energy threshold that the colliding molecules must exceed in order to react

question

if particles move faster they collide _____

answer

more often

question

reaction mechanism

answer

sequence of single reaction steps that sum to the overall equation

question

rate determining step limits

answer

how fast the overall reaction proceeds

question

reaction intermediate

answer

substance formed and used up during the reaction

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