CHM 142 Exam 1

Question 1

weakest of the intermolecular forces, present in all molecules

Answer 1

london-dispersion forces

Question 2

the attraction of the - and + charges of ions

Answer 2

dipole-dipole interactions

Question 3

when H is bonded to O N or F

Answer 3

hydrogen bonding

Question 4

attraction between an ion and a polar molecule, strongest of the forces

Answer 4

ion-dipole interaction

Question 5

when a dissolved solutes particles re-attatch in a solution to form a solid

Answer 5

crystallization

Question 6

a solution that has the amount of solute added that is measured by solubility

any more solute added will not dissolve

Answer 6

saturated

Question 7

the amount of solute needed to saturate a solution

max amt of solute that can be added

Answer 7

solubility

Question 8

the—the attraction between a solute and solvent the — the solubility of the solute in that solvent

Answer 8

stronger, greater

Question 9

does hydrogen bonding increase or decrease solubility?

Answer 9

Increases solubility

Question 10

liquids that mix in all proportions no matter the amount

Answer 10

miscible

Question 11

liquids that do not and can not mix

Answer 11

immiscible

Question 12

is the solublity of liquids and solids affected by pressure?

Answer 12

no, but gases are

Question 13

the solubility of a gas is — to its partial pressure

Answer 13

proportional

will increase if P increases, will decrease if P decreases

Question 14

solublity of a gas in a solvent=

Answer 14

K Pg

K= constant
P= partial pressure of gas

Question 15

how does temperature affect the solubility of gases?

Answer 15

as temperature increases the solublity of the gas decreases

gas escapes through bubbles when soln boils

Question 16

mass percentage =

Answer 16

mass of solute/ total mass of soln * 100

Question 17

ppm=

Answer 17

mass of solute/total mass of soln * 10^6

Question 18

ppb=

Answer 18

mass of solute/total mass of soln *10^9

Question 19

molality

Answer 19

moles of solute/ mass (Kg) of solvent

Question 20

molarity

Answer 20

moles of solute/ volume (L) of soln

Question 21

what do you need to convert to molarity if you’re using ppms or ppb

Answer 21

density

Question 22

is molality affected by increasing temp?

Answer 22

no, increasing temp does not change moles

it does affect molarity (V)

Question 23

properties that depend on the quantity (aka concentration) of molecules and not the identity of the molecule

vapor pressure, boiling point, freezing point, osmotic pressure

Answer 23

Colligative properties

Question 24

the pressre exerted by a gas over a liquid while in equilibrium

Answer 24

vapor pressure

Question 25

how do you calculate partial pressure?

Answer 25

total pressure * the mole fraction of the the moleucle

Question 26

when a solute is added to a pure solvent what happens to the vapor pressure?

Answer 26

the vapor pressure is lowered | less molecules can escape as gas so VP is lower

Question 27

vapor pressure of a soln=

Answer 27

pressure of solvent * mole fraction of solvent

Question 28

moles of component/ total moles

Answer 28

mole fraction

Question 29

is the boiling point of a solution lower or higher than that of a pure solvent?

Answer 29

it is (typically) higher than that of a pure solvent because the vapor pressure is lower so it takes a higher temp to boil the solution

Question 30

change in BP of a soln=

Answer 30

iKbm or boiling point of soln. - boiling point of the solvent

Question 31

the number of ions a molecule dissociates into when placed in a solvent

Answer 31

van hoff factor | it is 1 for nonelectrolytes

Question 32

is the freezing point of a solution higher or lower than the FP of a pure solvent?

Answer 32

it is lower than the pure solvent | think about icing roads and what the ice does to the water on the road

Question 33

Osmotic Pressure | equation

Answer 33

IMRT | i(n/v)RT

Question 34

Osmotic Pressure | defenition

Answer 34

the pressure needed to stop osmosis

Question 35

the movement of solvent molecules from a solution of low concentration (high solvent) to high concentration (low solvent)

Answer 35

osmosis

Question 36

what happens if two solutions are isotonic? | aka osmotic pressure is equal

Answer 36

No osmosis occurs

Question 37

what does it mean if a solution is hypertonic?

Answer 37

high osmotic pressure

Question 38

what does it mean if a solution is hypotonic?

Answer 38

low osmotic pressure

Question 39

dispersion of a soltue where the particles do not evenly/completely dissolve | intermediate kind of dispersion

Answer 39

colloids

Question 40

what allows colloids to be able to scatter light while solutions cannot?

Answer 40

the tyndall effect (and their larger molecules)

Question 41

all of the reactants exist in the same state of matter

Answer 41

Homogenous reactions

Question 42

the reactants exist in different states of matter

Answer 42

heterogenous reactions

Question 43

do heterogenous or homogenous reactions proceed at faster rates?

Answer 43

homogenous reactions

Question 44

how does concentration affect reaction rates?

Answer 44

the higher the concentration of reactants the quicker the reaction proceeds | more opportunities for mlecules to collide

Question 45

-change in concentration/ change in time | reactants

Answer 45

rate of dissappearnace

Question 46

rate of appearance | product

Answer 46

change in concentration/ change in time

Question 47

the rate of of a particlar instant/ point in time of a reaction

Answer 47

instantanous rate

Question 48

t=0

Answer 48

initial rate

Question 49

how do you calculate the instant rate when the products and reactants dont have a 1:1 ratio?

Answer 49

-1/a({A}/change in time)=1/b({B}/change in time)

Question 50

General Rate law

Answer 50

rate =k{A}^x*{B}^y

Question 51

the exponents x and y (or m and n) in the rate law equation that determine how the rate is affected by the reactants

Answer 51

reaction order

Question 52

when the rate depends on a single reactant to the 1st power

Answer 52

first order reaction

Question 53

rate=k{A}

Answer 53

rate law for first order reactions

Question 54

ln{A}=-kt+ln{A}0

Answer 54

Integrated rate law for first order reactions

Question 55

when the rate depends on one reactant to the second power or two reactants to the first order

Answer 55

second order reactions

Question 56

=K{A}^2

Answer 56

rate law for second order reactions

Question 57

integrated rate law for second order reactions

Answer 57

1/{A}=kt+1/{A}0

Question 58

when the rate of disappearance of a reactant is independent of concentration

Answer 58

Zeroth order reactions

Question 59

rate =k

Answer 59

rate law for zeroth order reactions

Question 60

=kt+{A}0

Answer 60

integrated rate law for zeroth reactions

Question 61

half-life for first order reactions

Answer 61

-ln(1/2)/k

Question 62

half-life for second order reactions

Answer 62

1/k{A}0

Question 63

rate laws relate --- and ---

Answer 63

rate and concentration

Question 64

integrated rate laws relate--- and ---

Answer 64

time and concentration

Question 65

molecules in a reaction must be aligned in the correct way to create a reaction/ form and break bonds

Answer 65

orientation factor

Question 66

the minimum energy required to complete a chemical reaction

Answer 66

activation energy

Question 67

the arrangment of molecules at the 'peak' of the Ea | not an intermediate

Answer 67

activation complex/transition state

Question 68

the --- the value of activation energy the --- the rate constant

Answer 68

lower, greater | or greater and lower

Question 69

fraction of molecules with the energy to reach the activation energy

Answer 69

f= e^(-Ea/RT)

Question 70

Arrhenius Equation

Answer 70

k=Ae^(-Ea/RT)

Question 71

equation for determining the activation energy when you have 1 rate constant

Answer 71

Ln(k)=-Ea/RT+ ln(A)

Question 72

eqaution for determing the activation energy when you have 2 rate constants

Answer 72

ln(k1/k2)=-Ea/R(1/T2-1/T1)

Question 73

reactions that occur in a single step/event

Answer 73

elementary reactions

Question 74

A---products | one step, one molecule

Answer 74

unimolecular

Question 75

A+B---products | or A+A---products

Answer 75

bimolecular

Question 76

true or false, the steps of a chemical reaction always add up/cancel out to a new reaction equation?

Answer 76

false, they will always result in the original equation

Question 77

not an initial reactant or intial product in the reaction, it is only seen in the reaction steps | and is used up in the steps

Answer 77

Intermediate

Question 78

for a mechansism with a slow first step rate law=

Answer 78

the rate of the slow first step

Question 79

a substance that is not affected/ used in a reaction that also increases the reaction rate | lowers activation E or changes orientation of molecules

Answer 79

catalyst

Question 80

when catalysts are in the same phase as the reactants

Answer 80

homogenous catalysis

Question 81

when the catalysts are in different phases than the reactants

Answer 81

heterogenous catalysis

Question 82

when molecules attatch to the bind to a surface | they do not permeate the inside

Answer 82

Adsorbtion

Question 83

biological molecules that use the Lock-in Key model and are very specific about what they choose to react with

Answer 83

Enzymes

Question 84

when reactants and product concentration is no longer changing but forward and reverse reactions are continuing to happen

Answer 84

equilibrium state

Question 85

Kc/Keq=

Answer 85

The concentration of products/ concentration of reactants to their coefficients

Question 86

How to calculate Kc/Keq for gases

Answer 86

Kp= Kc(RT)^change in moles | you can also use the pressures like you would use concentrations

Question 87

if Kc/Kp>>1 what does this indicate?

Answer 87

that the reaction favors the products | lies to the right, numerator is larger

Question 88

If Kc/Kp<<1 what does this indicate?

Answer 88

that the reaction favors the reactants | lies to the left, large denominator