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chemisty 2

Terms

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hydration
solvation when the solvent is water
saturated
a solution that is in equilibrium with undissolved solute
solubility
the amount of solute needed to form a sturated solution in a fiven quantity of solvent
unsaturated
contains less solute than a saturated solution
supersaturated
contains a greater amount of solute than needed to form a saturated solution
miscible
pairs of liquids such as acetone and water that mix in all proportions
immiscible
pairs of liquids that don not dissolve significantly in one another
Henry's law
the concentration of gas in a solution is proportinal to the pressure of gas over the solution.
mass percentage
=(mass of component in soln)/(total mass of soln) * 100
parts per million
= (mass of component in soln)/(total mass of soln) * 10^6
molality
= (moles solute)/(kg of solvent)
Raoult's law
the partial pressure exerted by solvent vapor above a solution equals the product of the mole fraction of the solvent in the solution times the vapor pressure of the pure solvent
molal boiling-point-elevation constant
a constant characteristic of a particular solvent that gives the change in boiling point as a functino of solution molality
molal freezing-point-depression constant
a constant characteristic of a particular solvent that gives the change in freezing point as a function of solution molality
osmosis
net movement of solvent molecules from the less concentrated solution into the more concentrated one. (net movement is always toward the solution with the higher solute concentration)
osmotic pressure
the pressure required to prevent osmosis
colloidal dispersions / colloids
intermediate types of dispersions or suspensions
hydrophilic
water loving
hydrophobic
water fearing
chemical kinetics
the area of chemistry concerned with the speeds at which reactions occur
instantaneous rate
the rate at a particular time as opposed to the average rate over an interval of time
first-order reaction
one whose rate depends on teh concentration of a single reactant raised to the first power
half-life
the time required for the concentration of a reactant to drop to one half of its intitial value
second-order reaction
one whose rate depends on the reactant concentration raised to the second power or on the concentrations of two different reactants, each raised to the first power
collision model
explains the factors influencing reaction rates in terms of the frequency of collisions, the number of collisions with energies exceeding the activation energy, and the probability that the coliisions occur with suitable orienttations.
activation energy
the minimum energy required to initiate a chemical reaction
activated complex / transition state
the particular arrangement of atoms at the top of the barrier
frequency factor
related to teh frequency of collisions and the probability that the collisions are favorably oreinted for the reaction
reaction mechanism
the process by which a reaction occurs
unimolecular
an elementary reaction that involves a single molecule
bimolecular
an elementary that involves two molecules
termolecular
an elementary reaction three molecules
rate-determining step
teh slow step limiting the overall reaction rate
catalyst
substance that chnages the speed of a chemical reaction without undergoing a permanent chmical change itself in teh process
homogenous catalyst
a catralyst that is present in teh same phase as the reacting molecules
heterogenouse catalyst
a catalyst that is in a different phase from that of the reactant substances
adsorption
the binding of molecules to a surface. usually the initial step in heterogeneous catalysis
active sites
the places where reacting molecules may become adsorbed
enzymes
a protein molecule that acts to catalyze specific biochemical reactions
substrates
the substances that undergo reaction at the active site
lock-and-key model
simple explanation for the specificity of enzymes
chemical equilibrium
occures when opposing reactions are proceeding at equal rates
homogenous equilibria
equilibria involving substances all in the same phase
heterogenous equilibria
equilibria involving substances in different phases
reaction quotient
the value that is obtained when concentrations of reactants and products are inserted into the equilibrium expression.
Le Châtelier's principle
if a system at equilibrium is disturbed by a change in temperature, pressure, or the concentration of one of the components, the system will shift its equilibrium position so as to counteract the effect of the disturbance.
Bronsted-Lowry acid
an acid can transfer a proton to another substance
Bronsted-Lowry base
a base can accept a proton
conjugate acid
formed by the addition of a proton to the base
conjugate base
formed by the removal of a proton from the acid
polyprotic acids
acids that have more than one ionizable H atom
amines
a compound that has the general formula R3N where R may be H or a hydrocarbon group
hydrolysis
a reaction with water. when a cation or anion eracts with water, it changes teh pH
amphoteric
capable of acting as either acids or bases
carboxylic acids
acids that contain a carboxyl group
Lewis acid
an electron-pair acceptor
Lewis base
an electron-pair donor
common-ion effect
the dissociation of a weak electrolyte is decreased by adding to the solution a strong electrolyte that has an ion in common with the weak electrolyte
buffered solutions / buffers
solutions that resist a change in pH upon addition of small amounts of acid or base
buffer capacity
the amount of acid or base the buffer can neutralize before the pH begins to chnage to an appreciable degree
complex ion
an assembly of a metal ion and the Lewis bases bonded to it
qualitative analysis
determines only the presence or absence of a particular metal ion
quantitative analysis
determines how much of a fiven substance is present
spontaneous
processes that occur without any outside intervention
reversible process
a process that can go back and forth between states along exactly the same path. a system at equilibrium is reversible becasue it can be reversed by an infinitesimal modification of a variable such as temperature
irreversible process
a process that cannot go back and forth between thermodynamic states along exactly the smae path. any spontaneous process
second law of thermodynamics
there is an inherent direction in which processes occur
isolated system
system that doesn't exchange energy or matter with its surroundings
translational motion
movement in which an entire molecule moves in a definite direction
vibrational motion
atoms within a molecule move periodically toward and away from on another
rotational motion
movement of a molecule as though it is spinning like a top
Third law of thermodynamics
the entropy of a pure crystallin substance at absolute zero is zero
standard molar entropies
the molar entropy values of substances in tehir standard states
Gibbs free energy
a thermodynamic state function that combines enthalpy and entropy.
oxidizing agent / oxidant
removes electrons from another substance by acquiring them itself
reducint agent / reductant
substance that gives up electrons causing another substance to be reduced
half-reactions
equations that show either oxidation or reductino alone
voltaic/galvanic cell
device in which the transfer of electrons takes place through an external pathway rather than directly between reactants
anode
electrode at which oxidation occurs
cathode
electrode at which reduction occurs
electromtive force
(emf) the potential difference between the two electrodes of a voltaic cell providing the driving force that pushes electrons through the external circuit
concentration cell
a cell based solely on the emf generated because of a difference in a concertration
battery
a portable, self-contained electrochemical power source that consists of one or more votaic cells
cathodic protection
protection of a metal by making it the cathode in an electrochemical cell
electrolysis reaction
a reaction in which a nonspontaneous redox reaction is brought about by the passage of current under a sufficient external electrical potential
electrolytic cells
place where electrolysis reactions occur
nucleons
subatomic particles in the nucleus, protons and neutrons
radionuclides
nuclei that are radioactive
radioisotopes
atoms that contain radionuclides
alpha particles
particles that are identical to helium-4 nuclei, consisting of two protons and two neutrons
beta particles
energetic electrons emitted from teh nucleus
gamma radiation
consisting of high energy photons, electromagnetic radiation of very short wavelength.
positron
a particle that has the same mass as an electron but an opposite charge
electron capture
the capture by the nucleus of an electron from teh electro cloud surrounding the nucleus
radioactive series / nuclear disintegration series
a series of nuclear reactions that begins with an unstable nucleus and terminates with a stableone.
magic numbers
numbers of protons and neutrons that result in very stable nuclei
nuclear transmutations
a conversion of one kind of nucleus to another
particle accelerators
a device that uses strong magnetic and electrostatic fields to accelerate charged particles
transurnaium elements
artificial transmutations that produce elements with atomic number above 92
activity
the rate at which a sample decays
geiger counter
device used to detect and measure radioactivity
scintillation counter
used to detect and measure radiation
radiotracer
a radioisotope that can be used to trace the path of an element
nuclear binding energy
the energy required to separate a nucleus into its individual nucleons
fusion
the joining of two light nuclei to form a more massive one
fission
the splitting of a large nucleus into two smaller ones
chain reactions
a series of reactions in which one reaction initiates the next
critical mass
teh amount of fissionable material large enough to maintain teh chain reaction with a constant rate of fission
supercritical mass
a mass in excess of a critical mass
ionizing radiation
radiation that causes ionization
nonionizing radiation
radiation that does not cause ionization
free radical
a substance with one or more unpaired electrons
alkanes
hydrocarbons that contain only single bonds
alkenes
hydrocarbons that contain a Carbon Carbon double bond
Alkynes
hydrocarbons that contain a Carbon Carbon triple bond
aromatic hydrocarbons
carbon atoms are connected in a planar ring structure
structural isomers
compounds with teh same molecular formula but with different bonding arrangements
geometric isomers
compounds that have teh same molecular formula nd teh same groups bonded to one another but differ in the spatial arrangment of these groups
addition reactions
a reactant is added to the two atoms that form the multiple bond
substitution reactions
one atom of a molecule is removed and replaced by another atom or group of atoms
functional group
a site of reactivity in an organic molecule
ethers
compounds in which two hydrocarbon groups are bonded to one oxygen
carbonyl group
Carbon Oxygen double bond
aldehydes
carbonyl group with at least one H atom attached
ketones
carbonyl group occurs at teh interior of a carbon chain
saponification
the hydrolysis of an ester in the presence of a base
ester
compounds in which the H atom of a carboxylic acid is replaced by a hydrocarbon group

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