Exam #2 vocab chem 1082 UMN
molecularity
# of species that must collide to produce the reaction represented by an elementary step in a reaction mechanism
5 factors that influence pka
1-size 2-electronegativity 3-inductive 4-resonance 5-hybridization
integrated 2nd order rate law
1/[A]=kt+1/[A]0
tetrahedral stereocenter
4 different groups bonded to the atom -most of the time is a carbon
relationship between Q and ksp
Q>ksp: precipitation occurs Q<ksp: no precipitation occurs
integrated 0 order rate law
[A]=-kt+[A]0
bronsted lowry base
accepts a proton (H+)
acidity constant (ka)
acid with larger ka is a stronger acid pka=-log(ka)
activated complex (aka transition state)
arrangement of atoms found at the top of the potential energy barrier as a reaction proceeds from reactants to products
ionizable
atom in side chain can gain or lose a proton to become charged
stereocenter
atom with the property that changing any 2 of its attached groups produces a different stereocenter
reaction rate
change in concentration of a reactant or product per unit time
adsorption
collection of 1 substance on the surface of another
enantiomers
configurational isomers that are mirror images of each other
diastereomers
configurational isomers that aren't mirror images of each other
racemic mixture
contains equal amounts of the positive and negative enantiomers of a chiral molecule
fisher projection
cross with horizontal line representing wedges and vertical line representing dashes
effective electronegativity
depends on hybridization increasing in the order of sp3< sp2< sp
inductive effect
distortion of electron density along covalent bonds brought about by the replacement of a hydrogen atom with another substituent
achiral
doesn't have an enantiomer(mirror image)
bronsted lowry acid
donates a proton
leveling effect
even if a solvent doesn't act as an acid or base in an intended proton transfer reaction- it can limit the existence of certain acids and bases in solution
heterogeneous catalyst
exists in a different phase than reacting molecules
differential rate law
gives the rate of a reaction as a function of concentrations
chiral
has an enantiomer(mirror image)
zwitterion
has both negative and positive formal charges- but a net charge of 0
constitutional isomers
have different physical properties and different chemical properties
configurational isomers
have same connectivity but differ in a way other than by rotations about single bonds -2 types: enantiomers and diastereomers
Le Shatty's principle
if a reaction at equilibrium experiences a change in reaction conditions (ie concentration, temperature, pressure, volume) then the equilibrium will shift to counteract the change
curved arrow notation
keeps track of valence electrons as they move throughout a mechanism
enzymes
large molecule (usually a protein) that catalyzes biological reactions
optically inactive
leave plane of polarization unchanged ie- achiral compounds
integrated 1st order rate law
ln[A]=-kt+ln[A]0
collision model
model based on idea that molecules must collide to react
meso compound
molecule with stereocenters but its achiral due to the presence of a plane of symmetry
chiral environment
nonsuperimposable upon its mirror image -chiral species must be present (other than the enantiomers of interest)
henderson-hasselbalch equation
pH=pka+log([base]/[acid]) -gives relationship between pH of an acid and base system and the concentrations of base and acid
absorption
penetration of 1 substance into another
homogeneous catalyst
present in the same phase as reacting molecules
rate constant (k)
proportionality constant in the relationship between reaction rate and reactant concentrations
1st order rate law
rate= -△[A]/△t=k[A] -plot of ln[A] vs time is always a straight line
2nd order rate law
rate=-△[A]/△t=k[A]^2
0 order rate law
rate=k[A]0=k(1)=k
bimolecular step
reaction involving the collision of 2 molecules
termolecular step
reaction involving the simultaneous collision of 3 molecules -rare
unimolecular step
reaction step only involving 1 molecule
elementary step
reaction whose rate law can be written from its molecularity
equilibrium constant (keq)
reactions tendency to form products
solubility product constant (ksp)
represents dissolving of an ionic solid in water
dextrorotatory
rotate light clockwise (to the right)
levorotatory
rotate light counterclockwise (to the left)
optically active
rotate the plane of polarization ie- enantiomerically pure chiral compounds
rate law
shows how the rate of reaction depends on the concentration of reactants
integrated rate law
shows the concentration of a reactant as a function of time
rate-determining step
slowest step in a reaction mechanism -the step that determines the overall rate -overall reaction can be no faster than slowest step in the sequence
buffered solution
solution that resists change in pH when either hydroxide ions or protons are added
conjugate base
species that acid becomes after losing a proton
conjugate acid
species that base becomes after picking up a proton
carbocations
species that contain a positively charged carbon atom (C+) -key intermediates in variety of chemical reactions
intermediate
species that is neither a product or reactant but is formed and consumed in the reaction sequence
chemical equilibrium
stationary state of a reaction where the concentrations of reactants and products don't change with time
catalyst
substance that speeds up a reaction without being consumed
achiral environment
superimposable upon its mirror image -no chiral species present (other than the enantiomers of interest) OR -chiral species (other than the enantiomers of interest) are present in equal proportions of their enantiomers
buffer capacity
the amount of H+ or OH- you can add to a buffer system without a significant change in pH
reaction mechanism
the series of elementary steps involved in a chemical reaction
activation energy
threshold energy that must be overcome to produce a chemical reaction
half life of a reactant
time required for a reactant to reach half of its original concentration t1/2=0.693/k
instantaneous rate
value of the rate at a particular time
