Exam #2 vocab chem 1082 UMN

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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


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