Chem Final

Front 1

solution

Back 1

a homogenous mixture of two or more substances

Front 2

solvent

Back 2

the majority component in a solution

Front 3

solute

Back 3

the minority component in a solution

Front 4

aqueous solution

Back 4

water is the solvent and a solid, liquid or gas is the solute

Front 5

solubility

Back 5

the amount of the substance that will dissolve in a given amount of solvent

Front 6

entropy

Back 6

a measure of energy randomization or energy dispersal in a system

Front 7

enthalpy of solution

Back 7

the enthalpy change associated with a substance dissolving into a solvent

Front 8

heat of hydration

Back 8

the enthalpy change that occurs when 1 mol of the gaseous solute ions are dissolved in water

Front 9

saturated solution

Back 9

a solution in which the dissolved solute is in dynamic equilibrium with the solid or undissolved solute

if you add additional solute, it will not dissolve

Front 10

unsaturated solution

Back 10

a solution containing less than the equilibrium amount of solute

if you add additional solute, it will dissolve

Front 11

supersaturated solution

Back 11

a solution containing more than the equilibrium amount of solute

Front 12

recrystallization

Back 12

a technique used to purify solids in which the solid is put into hot solvent until the solution is saturated; when the solution cools the purified solute comes out of the solution

Front 13

Henry's law

Back 13

S_gas = (K_h)(P_gas)

Front 14

dilute solution

Back 14

a solution containing small quantities of solute relative to the amount of solvent

Front 15

concentrated solution

Back 15

a solution containing large quantities of solute relative to the amount of solvent

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Molarity (M)

Back 16

mol/L

amount of solute in mol /

volume of solution in L

Front 17

molality (m)

Back 17

mol/kg

amount of solute in mol /

mass of solvent in kg

Front 18

mole fraction (x)

Back 18

mol/mol

amount of solute in mol /

total amount of solute and solvent in mol

Front 19

mole percent (mol %)

Back 19

mole fraction x 100%

Front 20

parts per million by mass

Back 20

multiplication factor = 10^6

ppm

Front 21

parts per billion by mass

Back 21

multiplication factor = 10^9

ppb

Front 22

parts by volume

Back 22

volume solute /

volume solution x

multiplication factor

Front 23

colligative property

Back 23

a property that depends on the number of particles dissolved in solution, not on the type of particle

ie: the lowering of the melting point of ice by salt

Front 24

Raoult's law

Back 24

P_solution = X_solvent P_solvent

Front 25

vapor pressure lowering

Back 25

the difference in vapor pressure between the pure solvent and the solution

Front 26

ideal solution

Back 26

a solution that follows Raoult's law at all concentrations for both the solute and the solvent

is similar to an ideal gas following the ideal gas law

Front 27

freezing point depression

Back 27

colligative property

process in which adding a solute to a solvent decreases the freezing point of the solvent

Front 28

boiling point elevation

Back 28

occurs when the boiling point of a solution becomes higher than the boiling point of a pure solvent

Front 29

osmosis

Back 29

the flow of solvent from a solution of lower solute concentration to one of higher solute concentration

Front 30

semipermeable membrane

Back 30

a membrane that selectively allows some substances to pass through but not others--separates the two halves of the cell

Front 31

osmotic pressure

Back 31

the pressure required to stop the osmotic flow

Front 32

crystalline

Back 32

atoms or molecules that are arranged in a well-ordered three dimensional array

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amorphous

Back 33

atoms or molecules arranged with no long range order

Front 34

dispersion force

Back 34

fluctuations in the electron distribution within molecules or atoms. Since all atoms and molecules have electrons, they all exhibit dispersion forces

weakest of all intermolecular forces

Front 35

dipole-dipole force

Back 35

an intermolecular force exhibited by polar molecules that results from the uneven charge distribution

Front 36

permanent dipole

Back 36

a permanent separation of charge; a molecule with a permanent dipole always has a slightly negative charge at one end and slightly positive charge on the other end

Front 37

miscibility

Back 37

the ability to mix without separating into two phases- of liquids

Front 38

hydrogen bonding

Back 38

polar molecules containing hydrogen atoms bonded directly to small electronegative atoms-- most importantly F,O, or N.

super dipole-dipole force

NOT A CHEMICAL BOND

Front 39

ion-dipole force

Back 39

occurs when an ionic compound is mixed with a polar compound and is especially important in aqueous solutions of ionic compounds

Front 40

surface tension

Back 40

the energy required to increase the surface area by a unit amount

tendency for liquids to minimize their surface creates a kind of skin at the surface that resists penetration

decreases with decreasing intermolecular forces

Front 41

viscosity

Back 41

the resistance for liquid to flow

increases with increasing intermolecular forces

Front 42

capillary action

Back 42

the ability of a liquid to flow against gravity up a narrow tube

the attraction between molecules in a liquid are called cohesive forces

the attraction between the molecules in the liquid and the surface in the tube are called adhesive forces

Front 43

vaporization

Back 43

the process by which thermal energy can overcome intermolecular forces and produce a state change from liquid to gas

condensation is the opposite

increases with increasing temperature

increases with increasing surface area

increases with decreasing strength of intermolecular forces

endothermic

Front 44

condensation

Back 44

the transition from gas to liquid

vaporization is the opposite

exothermic

Front 45

volatile

Back 45

liquids that vaporize easily

weak intermolecular forces

Front 46

nonvolatile

Back 46

liquids that do not vaporize easily

Front 47

heat of vaporization (enthalpy)

Back 47

the amount of heat required to vaporize one mole of a liquid to gas

endothermic

always positive

Front 48

dynamic equilibrium

Back 48

the rate of condensation and the rate of vaporization become equal

Front 49

vapor pressure

Back 49

the pressure of a gas in dynamic equilibrium with its liquid

Front 50

boiling point

Back 50

the temperature at which a liquids vapor pressure equals the external pressure

"normal" is the temperature at which its vapor pressure equals 1 atm

Front 51

Clausius-Clapeyron equation

Back 51

gives a linear relationship between the natural log of the vapor pressure and the inverse of the temperature

Front 52

critical temperature

Back 52

the temperature above which a liquid cannot exist, regardless of pressure

Front 53

critical pressure

Back 53

the pressure required to bring about a transition to a liquid at the critical temperature

Front 54

sublimation

Back 54

the transition from a solid to gas

endothermic

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deposition

Back 55

the transition from a gas to solid

exothermic

Front 56

melting point

Back 56

the molecules have enough thermal energy to overcome the intermolecular forces that hold them at their stationary points and the solid turns into a liquid

Front 57

melting (fusion)

Back 57

the transition from solid to liquid

endothermic

Front 58

freezing

Back 58

the transition from liquid to solid

exothermic

Front 59

heat of fusion

Back 59

the amount of heat required to melt 1 mol of a solid

positive because it is endothermic

Front 60

phase diagram

Back 60

a map of the state of a substance as a function of pressure and temperature

Front 61

triple point

Back 61

unique set of conditions at which three states are equally stable and in equilibrium

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critical point

Back 62

represents the temperature and pressure above which a supercritical fluid exists

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crystalline lattice

Back 63

the regular arrangement of atoms in a crystalline solid

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unit cell

Back 64

a small collection of atoms, ions, or molecules within the crystalline lattice

Front 65

simple cubic

Back 65

a unit cell that consists of a cube with one atom at each corner

1 atom/unit cell

coordination #6

l=2r

packing effeciency = lowest 52%

Front 66

coordination number

Back 66

the number of atoms with which each atom in a crystal lattice is in direct contact

Front 67

packing efficiency

Back 67

the percentage of volume of a unit cell occupied by the atoms, assumed to be spherical

Front 68

body-centered cubic

Back 68

a unit cell that consists of a cube with one atom at each corner and one atom at the center of the cube

atoms/unit cell = 2

coordination # 8

l = 4r/√3

packing efficiency = middle 68%

Front 69

face-centered cubic

Back 69

a crystal structure whose unit cell consists of a cube with one atom at each corner and one atom in the center of every face

atom/unit cell = 4

coordination # 12

l= 2√2r

packing efficiency = highest 74%

Front 70

hexagonal closest packing

Back 70

a closest packed arrangement in which the atoms of the third layer align exactly over those in the first layer

Front 71

cubic closest packing

Back 71

a closest packed arrangement in which the third layer of atoms is offset from the first; the same structure as the face-centered cubic

Front 72

molecular solids

Back 72

solids whose composite units are molecules; they generally have low melting points

Front 73

ionic solids

Back 73

solids whose composites units are ions; they generally have high melting points

Front 74

atomic solids

Back 74

solids whose composite units are atom; they include nonbonding atomic solids, metallic atomic solids, and network covalent solids

Front 75

nonbonding atomic solids

Back 75

atomic solids held together by dispersion forces; they have low melting points

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metallic atomic solids

Back 76

atomic solids held together by metallic bonds; they have variable melting points

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network covalent atomic solids

Back 77

atomic solids held together by covalent bonds; they have high melting points

Front 78

band theory

Back 78

a model for bonding in atomic solids that comes from molecular orbital theory in which atomic orbitals combine and become delocalized over the entire crystal

Front 79

band gap

Back 79

an energy gap that exists between the valence band and conduction band of semiconductors and insulators

Front 80

rate law

Back 80

a relationship between the rate of a reaction and the concentration of the reactants

Front 81

rate constant (k)

Back 81

a constant of proportionality in the rate law

Front 82

reaction order

Back 82

a value in the rate law that determines how the rate depends on the concentration of the reactants

Front 83

overall order

Back 83

the sum of the orders of all reactants in a chemical reaction

Front 84

integrated rate law

Back 84

a relationship between the concentrations of the reactants in a chemical reaction and time

Front 85

half-life (t_1/2)

Back 85

the time required for the concentration of a reactant or the amount of a radioactive isotope to fall to one half of its initial value

Front 86

Arrhenius equation

Back 86

an equation which relates the rate constant of a reaction to the temperature, the activation energy, and the frequency factor

k = Ae^-E_a/RT

Front 87

activation energy

Back 87

an energy barrier in a chemical reaction that must be overcome for the reactants to be converted into products

Front 88

frequency factor

Back 88

the number of times that the reactants approach the activation energy per unit time

Front 89

activated complex (transition state)

Back 89

a high energy intermediate state between reactant and product

Front 90

exponential factor

Back 90

a number between 0 and 1 that represents the fraction of molecules that have enough energy tom make it over the activation barrier on a given approach

Front 91

Arrhenius plot

Back 91

a plot of the natural log of the rate constant (ln k) vs the inverse of the temperature in K (1/T) that yields a straight line with a slope of -E_a/R and a y-intercept of ln A.

Front 92

collision model

Back 92

a model of chemical reactions in which a reaction occurs after a sufficiently energetic collision between two reactant molecules.

Front 93

orientation factor

Back 93

in the collision model, the percentage of sufficiently energetic collisions that succeed in forming the product based upon the orientation of the molecules

Front 94

collision frequency

Back 94

in the collision model; the number of collisions that occur per unit of time

Front 95

reaction mechanism

Back 95

a series of individual chemical steps by which an overall chemical reaction occurs

Front 96

elementary step

Back 96

an individual step in a reaction mechanism

Front 97

reaction intermediates

Back 97

species that are formed in one step of a reaction mechanism and consumed in another

Front 98

molecularity

Back 98

the number of reactant particles involved in an elementary step

Front 99

unimolecularity

Back 99

describes a reaction that involves only one particle that goes on to form products

Front 100

bimolecularity

Back 100

a elementary step in a reaction that involves two particles, either the same species or different, that collide and go on to form products

Front 101

termolecular

Back 101

an elementary step of a reaction in which three particles collide and go on to form products

Front 102

rate-determining step

Back 102

the step in the reaction mechanism that occurs much more slowly than than any of the other steps

Front 103

catalyst

Back 103

a substance that is not consumed in a chemical reaction, but increases the rate of the reaction by providing an alternate mechanism in which rate-determining step has a smaller activation energy

Front 104

homogeneous catalysis

Back 104

catalysis in which the catalyst exists in the same phase as the reactants

Front 105

heterogeneous catalysis

Back 105

catalysis in which the catalyst and the reactants exist in different phases

Front 106

enzyme

Back 106

a biochemical catalyst made of protein that increases the rates of biochemical reactions

Front 107

active site

Back 107

the specific area of an enzyme at which catalysis occurs

Front 108

substrate

Back 108

the reactant molecule of a biochemical reaction that binds to an enzyme at the active site

Front 109

reversible

Back 109

as applied to a reaction, the ability to proceed in either the forward or reverse direction

Front 110

dynamic equilibrium

Back 110

the point at which the forward and reverse reactions are equal

Front 111

equilibrium constant (K)

Back 111

the ratio, at equilibrium, of the concentrations of the products of a reaction raised to their stoichiometric coefficients to the concentrations or the reactants raised to their stoiciometric coefficients

Front 112

law of mass action

Back 112

the relationship between the balanced chemical equation and the expression of the equilibrium constant

Front 113

reaction quotient (Q)

Back 113

the ratio, at any point in the reaction, of the concentration of the products of a reaction raised to their stoiciometric coefficiencts to the concentrations of the reactants raised to their stoichiometric coefficients

Front 114

Le Chatelier's principle

Back 114

the principle stating that when a chemical system at equilibrium is disturbed, the system shifts in a direction that minimizes the disturbance

Front 115

carboxylic acid

Back 115

an organic acid containing the functional group-COOH

Front 116

alkaloid

Back 116

organic bases found in plants; they are often poisonous

Front 117

Arrhenius definitions of acids and bases

Back 117

the definitions of an acid as a substance that produces H+ ions in aqueous solution and a base as a substance that produces OH- ions in aqueous solution

Front 118

hydronium ion

Back 118

H3O+, the ion formed from the association of a water molecule with an H+ ion donated by an acid

Front 119

Bronsted-Lowry definitions of acids and bases

Back 119

acid as a proton (H+ ion) donor

base as a proton acceptor

Front 120

amphoteric

Back 120

able to act as an acid or base

Front 121

conjugate acid-base pair

Back 121

two substances related to each other by the transfer of a proton

Front 122

strong acid

Back 122

an acid that completely ionizes in solution

Front 123

weak acid

Back 123

an acid that does no completely ionize in water

Front 124

monoprotic acid

Back 124

an acid that contains only one ionizable proton

Front 125

diprotic acid

Back 125

an acid that contains two ionizable protons

Front 126

triprotic acid

Back 126

an acid that contains three ionizable protons

Front 127

acid ionization constant (K_a)

Back 127

the equilibrium constant for the ionization reaction of a weak acid; used to compare the relative strengths of weak acids

Front 128

autoionization

Back 128

the process by which water acts as an acid and a base with itself

Front 129

ion product constant for water (K_w)

Back 129

the equilibrium constant for the auto-ionization of water

Front 130

neutral

Back 130

the state of a solution where the concentrations of H30+ and OH- are equal

Front 131

acidic solution

Back 131

a solution containing an acid that creates additional H3O+ ions, causing [H30+] to increase

Front 132

basic solution

Back 132

a solution containing a base that creates additional OH- ions, causing the [OH-] to increase

Front 133

pH

Back 133

the negative log of the concentration of H3O+ in a solution; the pH scale is a compact way to specify the acidity of a solution

Front 134

polyprotic acid

Back 134

an acid that contains more than one ionizable proton and releases them sequentially

Front 135

percent ionization

Back 135

the concentration of ionized acid in a solution divided by the initial concentration of acid multiplied by 100%

Front 136

strong base

Back 136

a base that completely dissociates in solution

Front 137

weak base

Back 137

a base that only partially ionizes in water

Front 138

Lewis acid

Back 138

an atom, ion, or molecule that is an electron pair acceptor

Front 139

Lewis base

Back 139

an atom, ion, or molecule that is an electron pair donor

Front 140

buffer

Back 140

a solution containing significant amounts of both a weak acid and its conjugate base that resists pH change by neutralizing added acid or added base

Front 141

common ion effect

Back 141

the tendency for a common ion to decrease the solubility of an ionic compound or to decrease the ionization of a weak acid or weak base

Front 142

Henderson-Hasselbalch equation

Back 142

an equation used to easily calculate the pH of a buffer solution from the initial concentrations of the buffer components

pH=pKa + log [base]/[acid]

Front 143

buffer capacity

Back 143

the amount of acid or base that can be added to a buffer without destroying its effectiveness

Front 144

acid-base titration

Back 144

a laboratory procedure in which a basic or acidic solution of unknown concentration is reached with an acidic or basic solution of known concentration, in order to determine the concentration of the unknown

Front 145

indicator

Back 145

a dye whose color depends on the pH of the solution it is dissolved in; often used to detect the endpoint of a titration

Front 146

equivalence point

Back 146

the point in a titration at which the added reactant completely reacts with the reactant present in the solution; for acid-base titrations, the point at which the amount of acid is stoichiometrically equal to the amount of base in solution

Front 147

endpoint

Back 147

the point of pH change where an indicator changes color

Front 148

solubility product constant (Ksp)

Back 148

the equilibrium expression for a chemical equation representing the dissolution of a slightly to moderately soluble ionic compound

Front 149

molar solubility

Back 149

the solubility of a compound in units of moles per liter

Front 150

complex ion

Back 150

an ion that contains a central metal ion bound to one or more ligands

Front 151

ligand

Back 151

a neutral molecule or an ion that acts as a Lewis base with the central metal ion in a complex ion.

Front 152

formation constant (K-f)

Back 152

the equilibrium constant associated with reactions for the formation of complex ions

Front 153

spontaneous process

Back 153

a process that occurs without ongoing outside interventions

Front 154

entropy

Back 154

a thermodynamic function that is proportional to the number of energetically equivalent ways to arrange the components of a system to achieve a particular state; a measure of the energy randomization or energy dispersal in a system

Front 155

second law of thermodynamics

Back 155

a law stating that for any spontaneous process , the entropy of the universe increases

Front 156

Gibbs free energy (G)

Back 156

a thermodynamic state function related to enthalpy and entropy by the equation G=H-TS; chemical systems tend towards Gibbs free energy , also called the chemical potential

Front 157

standard entropy change for a reaction

(G_rxn)

Back 157

the change in entropy for a process when all reactants and products are in their standard states

Front 158

free energy of formation

(G_f)

Back 158

the change in free energy when 1 mol of a compound forms from its constituent elements in their standard states

Front 159

electrical current

Back 159

the flow of electric charge

Front 160

electrochemical cell

Back 160

a device in which a chemical reaction either produces or is carried out by electrical current

Front 161

voltaic (galvanic) cell

Back 161

a electrochemical cell which produces electrical current from a spontaneous chemical reaction

Front 162

electrolytic cell

Back 162

an electrochemical cell which uses electrical current to drive a non-spontaneous chemical reaction

Front 163

half-cell

Back 163

one half of an electrochemical cell where either oxidation or reduction occurs

Front 164

electrode

Back 164

a conductive surface that allows electrons to enter or leave half-cells.

Front 165

ampere (A)

Back 165

the SI unit for chemical current ; 1A = 1C/s

Front 166

potential difference

Back 166

a measure of the difference in potential energy usually in joules per unit of charge (coulombs)

Front 167

volt (V)

Back 167

the SI derived unit for potential difference and equal to 1 J/C

Front 168

electromotive force (emf)

Back 168

the force that results in the motion of electrons due to a difference in potential

Front 169

cell potential (cell emf) (E_cell)

Back 169

the potential difference between the cathode and the anode in an electrochemical cell

Front 170

standard cell potential

(standard emf)

(E^o_cell)

Back 170

the cell potential for a system in standard states (solute concentration of 1 M and gaseous reactant partial pressure of 1 atm)

Front 171

anode

Back 171

the electrode in an electrochemical cell where oxidation occurs; electrons flow away from the anode

Front 172

cathode

Back 172

the electrode in an electrochemical cell where reduction occurs; electrons flow toward the cathode

Front 173

salt bridge

Back 173

an inverted U shaped tube containing a strong electrolyte such as KNO3 that connects the two half cells allowing a flow of ions that neutralizes the charge buildup

Front 174

standard electrode potential

Back 174

the standard cell potential of an individual half-cell

Front 175

standard hydrogen electrode

Back 175

the half-cell consisting of an inert platinum electrode immersed in 1 M HCl with hydrogen gas at 1 atm bubbling through the solution; used as the standard of a cell potential of zero

Front 176

Faraday's constant (F)

Back 176

the charge in coulombs of 1 mol of electrons

F = 96500 C/mol e-

Front 177

Nernst equation

Back 177

the equation relating the cell potential of an electrochemical cell to the standard cell potential and the reaction quotient

E_cell = E^o_cell - 0.0592V/n (log Q)

Front 178

dry-cell battery

Back 178

a battery that does not contain a large amount of liquid water, often using the oxidation of zinc and the reduction of MnO2 to provide an electrical current.

Front 179

alkaline battery

Back 179

a dry cell battery that employs the oxidation of zinc and the reduction of manganese(IV) oxide in a basic medium

Front 180

lead-acid storage battery

Back 180

a battery that uses the oxidation of lead and the reduction of lead (IV) oxide in sulfuric acid to provide electrical current

Front 181

nickel-cadmium battery (NiCad)

Back 181

a battery that consists of an anode composed of solid cadmium and a cathode composed of NiO(OH) in a KOH solution

Front 182

lithium ion battery

Back 182

a rechargeable battery that produces electrical current from the motion of lithium ions from the anode to the cathode

Front 183

fuel cell

Back 183

a voltaic cell in which the reactants continuously flow through the cell

Front 184

electrolysis

Back 184

the process by which electrical current is used to drive an otherwise non-spontaneous redox reaction

Front 185

corrosion

Back 185

the gradual, nearly always undesired oxidation of metals that occurs when they are exposed to oxidizing agents in the environment