Quant. Analysis

Flashcard maker : Marie Florence
Enthalpy Change
heat absorbed or released when a rxn. occurs at constant pressure
Endothermic Rxn.
one for which delta H is positive, heat must be supplied to reactants for them to react
Exothermic Rxn.
one for which delta H is negative, heat is liberated when products formed
Entropy
a measure of the “disorder” of a substance
Gibbs Free Energy
for any process at constant temp. is related to change in enthalpy, determines if there’s net driving force for reactants or products to be formed
Le Chatelier’s Principle
if a system at equilibrium’s disturbed, the direction it proceeds back to equilibrium is such that disturbance is partly offset
Rxn. Quotient Q
expression having same form as equilibrium constant for rxn.
Solubility Product Ksp
equilibrium constant for dissociation of solid salt to give its ions in soln.
Common Ion Effect
occurs when salt’s dissolved in soln. already containing one of the ions of salt, application of Le Chatelier’s Principle
Coprecipitation
occurs when substance whose solubility not exceeded precipitates along w/one whose solubility is exceeded
Complex Ions
ions containing two + ions or molecules that are each stable by themselves
Ligand
an atom or group attached to central atom in molecule, or attached to anything else of interest
Lewis Acid
e- acceptor
Lewis Base
e- donor
Adduct
product formed when Lewis Base combines w/Lewis Acid
Arrhenius Acid
produces hydronium ion or H30+ in aqueous solns.
Arrhenius Base
produces OH- in aqueous solns.
Bronsted-Lowry Acid
a proton donor
Bronsted-Lowry Base
a proton acceptor
Salt
an ionic solid
Autoprotolysis
rxn. which 2 molecules of same species transfer a proton from one to the other
Protic Solvents
ones w/acidic H atoms
Aprotic Solvents
ones that cannot donate protons in an acid-base rxn.
Polyprotic Acids and Bases
compounds that can donate or accept more than one proton
Acid
substance that inc. the concentration of H+ when added to water
Acidic Soln.
one which activity of H+ > activity of OH-
Base
substance that dec. the concentration of H+ when added to water
Basic Soln.
one which activity of OH- > activity of H+
Spectroscopy
study of interaction of light and matter
Spectrophotometry
any method using light to measure chemical concentrations
Electromagnetic Spectrum
whole range of electromagnetic radiation, including visible light, radio waves, x-rays, etc.
Planck’s Constant
fundamental constant of nature equal to energy of light divided by freq.
Ground State
state of atom/molecule w/minimum possible energy
Excited State
any state of atom/molecule having more than minimum possible energy
Photon
particle of light w/energy hv (h = Planck’s constant and v = freq.)
Irradiance
power per unit area of beam of electromagnetic radiation
Transmittance
radiant power go light striking sample on one side divided by radiant power of light emerging from other side of sample
Absorbance
logarithmic comparison of radiant power of light on one side divided by radiant power of light emerging from other side
Beer-Lambert Law
relates absorbance of sample to concentration, pathlength, and molar absorptivity
Cuvet
cell w/transparent walls used to hold samples for spectrophotometric measurements
Spectrophotometric Analysis
any method which light absorption, emission, reflection, pr scattering’s used to measure chemical concentrations
Spectrophotometric Titrations
one which absorption of light’s used to monitor progress of titration rxn. and to find equilibrium pt.
Molecular Orbitals
describes distribution of an e- w/in a molecule
Electronic Transition
one which e- is promoted from one energy level to another
Singlet State
one which all e- spins are paired
Triplet State
electronic state which there are two unpaired e-
Vibrational Transition
occurs when molecule changes its vibrational energy
Rotational Transition
occurs when molecule changes its rotational energy
Internal Conversion
radiationless, isoenergetic, electronic transition b/w states of same e- spin multiplicity
Intersystem Crossing
radiationless, isoenergetic, electronic transition b/s states of diff. e- spin multiplicity
Fluorescence
process which molecule emits photon after absorbing photon and results from transition b/w states of same spin multiplicity
Phosphorescence
emission of light during transition b/w states of diff. spin multiplicity, and is slower than fluorescence
Luminescence
any emission of light by a molecule
Chemiluminescence
emission of light by an excited-state product of chemical rxn.
Immiscible
2 liquids that do not form a single phase when mixed together
Miscible
2 liquids that form a single phase when mixed in any ratio
Solvent Extraction
method in which chemical species transferred from one liquid phase to another, used to separate components of a mixture
Extraction
process which solute’s transferred from one phase to another
Chromatography
technique in which molecules in mobile phase separated bc of their diff. affinities for a stationary phase
Mobile Phase
in chromatography, phase that travels through column
Stationary Phase
in chromatography, phase that does not move through column
Eluent
solvent applied to beginning of chromatography column
Eluate
what comes out of chromatography column
Elution
process of passing a liquid or gas through a chromatography column
Packed Column
chromatography column filled w/stationary phase particles
Open Tubular Column
in chromatography, capillary column whose walls are coated w/stationary phase
Adsorption Chromatography
technique in which solute equilibrates b/w mobile phase and adsorption sites on stationary phase
Partition Chromatography
technique in which separation’s achieved by equilibration of solute b/w phases
Ion-Exchange Chromatography
technique in which solute ions retained by oppositely charged sites in stationary phase
Molecular Exclusion Chromatography
technique in which stationary phase has porous structure into which sm. molecules can enter but lg. molecules cannot, so lg. molecules move faster
Affinity Chromatography
technique in which a particular solute’s retained by a column by virtue of a specific interaction w/a molecule covalently bound to stationary phase
Volume Flow Rate
volume of mobile phase per unit time eluted from the column
Linear Flow Rate
the distance per unit time traveled by the mobile phase
Chromatogram
graph showing chromatography detector response as a fxn. of elution time or volume
Retention Time
the time, measured from injection, needed for a solute to be eluted from a chromatography column
Retention Volume
the volume of solvent needed to elute a solute from a chromatography column
Adjusted Retention Time
the additional time required for a solute to travel the length of the column beyond the time required for unretained solvent
Relative Retention
ratio of adjusted retention times for 2 components
Capacity/Retention Factor
adjusted retention time for a peak divided by the time for the mobile phase to travel through the column
Partition Coefficient
equilibrium constant for rxn. in which solute’s partitioned b/w 2 phases
Resolution
how close 2 bands in a spectrum/chromatogram can be to each other and still be seen as 2 peaks, and diff. in retention times of adjacent peaks divided by their width in chromatography
Diffusion
net transport of solute from region of high to low concentration caused by random movement of molecules in a liquid or gas
Diffusion Coefficient
the rate at which a substance moves randomly from region of high to lower concentration
Plate Height
length of chromatography column divided by number of theoretical plates in column
Separation Factor/Relative Retention
quotient of linear velocities of 2 solutes
van Deemter Equation
describes dependence of chromatographic plate height on linear flow rate
Longitudinal Diffusion
diffusion of solute molecules parallel to direction of travel through chromatography column

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