Quant Final Exam Flashcards
what; process of determining the identity of the constituents of a substance
Qualitative
how much; process of measuring how much of a constituent is present in a substance
Quantitative
substance being measured or detected; also called measurand
Analyte
a solution whose composition is known by virtue of the way that it was made from a reagent of known purity or by virtue of its reaction with a known quantity of a standard reagent
Standard Solution
liquid remaining above the solid after a precipitation
Supernatant
portion
Aliquot
a solution of anything in water
Aqueous
a suspension of a solid in a solvent
Slurry
to pour liquid off a solid or, perhaps, a denser liquid; the denser phase is left behind
Decant
General Steps in Chemical Analysis:
Step One
formulating the question (translating questions into specific questions)
General Steps in Chemical Analysis:
Step Two
selecting analytical procedures (literature search)
General Steps in Chemical Analysis:
Step Three
sampling (selecting representative materials)
General Steps in Chemical Analysis:
Step Four
sample preparation (converting sample into suitable form)
General Steps in Chemical Analysis:
Step Five
analysis (repeated measurements, applying different analytical methods if possible)
General Steps in Chemical Analysis:
Step Six
reporting and interpretation
General Steps in Chemical Analysis:
Step Seven
drawing conclusions
Avogadro’s Number
6.022E23
Molarity Formula
moles solute / liters solution
Molality Formula
moles solute / kilograms solvent
If the mobile phase is polar, which sample elutes first? The polar or nonpolar sample?
polar
Which elutes first in a cathode? Anions or cations?
anions
Weight Percent Formula
(mass solute / mass solution) x 100
Part Per Million Formula
(mass solute / mass solution) x 10E6
Part Per Billion Formula
(mass solute / mass solution) x 10E9
Dilution Formula
M1V1 = M2V2 (or C1V1 = C2V2)
Dilution Factor
sample volume / total volume
chemical analysis based on weighing a final product
Gravimetric Analysis
In addition and subtraction, how is the number of significant figures determined?
the last sig fig is determined by the number with the fewest decimal places
(EX: 5.3 + 16.41 = 21.7)
In multiplication and division, how is the number of significant figures determined?
the number with the fewest sig figs determines the number of sig figs in the final answer
(EX: 6.3 x 2.761 = 17)
In logarithms, how is the number of significant figures determined?
the number of significant figures in the final answer is equal to the number of sig figs in the mantissa
(EX: log(339) = 2.530 ; 10 ^ 2.530 = 339)
(NOTE: sig figs begin after the decimal; antilog is the opposite)
built-in error, consistent, and reproducible; in principle, detectable and correctable
(EX: improperly standardized balance, incorrectly prepared standard solutions)
Systematic Error
error from uncontrollable variables in the measurement; inconsistent error value; can be reduced by repeated trials but cannot be completely eliminated
(NOTE: sometimes expressed as standard deviation)
Random Error
how close a measurement is to the true/accepted value; nearness to the truth
Accuracy
how close together a set of measurements are; reproducibility
Precision
Relative Uncertainty Formula
absolute uncertainty / magnitude of measurement
Percent Relative Uncertainty Formula
relative uncertainty x 100
the actual amount by which a quantity is uncertain; usually given in parentheses by the given measurements
Absolute Uncertainty
Propagation of Error for Addition and Subtraction
e = sqrt( (e1)^2 + (e2)^2 + (e3)^2 )
Propagation of Error for Multiplication and Division
%e = sqrt( (%e1)^2 + (%e2)^2 + (%e3)^2 )
Which test compares mean values? F-Test or t-Test?
t-Test
Which test compares standard deviations? F-Test or t-Test?
F-Test
When does precipitation occur?
Q > Ksp
Equilibrium Constant Formula (K)
[products] / [reactants]
(NOTE: don’t forget the stoichiometric exponents when applicable)
Equilibrium Constant for Reversed Reactions
K’ = 1 / K
Equilibrium Constant for Added Reactions
K = K1 x K2
When is a reaction favored?
K > 1 ; G is negative
What does negative enthalpy mean?
exothermic
What does positive enthalpy mean?
endothermic
What does positive entropy mean?
products have greater entropy than reactants
What does negative entropy mean?
reactants have greater entropy than products
When is a reaction disfavored?
K < 1 ; G is positive
What does negative G mean?
a spontaneous reaction
What does positive G mean?
not a spontaneous reaction
if a system at equilibrium is disturbed, the direction in which it proceeds back to equilibrium is such that the disturbance is offset
Le Chatelier’s Principle
the equilibrium constant for the reaction in which a solid salt dissolves to give its constituent ions in solution
Solubility Product (Ksp)
a salt is less soluble if one of its constituent ions is already present in the solution
Common Ion Effect
When Q > K what direction will the reaction proceed?
Left
When Q < K what direction will the reaction proceed?
Right
electron pair acceptor
Lewis Acid
electron pair donor
Lewis Base
When ionic strength increases, what happens to the activity coefficient?
Decreases
When ion charge increases, what happens to the activity coefficient?
Decreases
When ion size increases, what happens to the activity coefficient?
Increases
Ionic Strength Formula (mu)
(1/2) x SUM( C1(Z1)^2 + C2(Z2)^2… )
True or False: Strong acids/bases dissociate completely.
True
True or False: Weak acids/bases only partially dissociate.
True
True or False: A stronger acid (HA) means a weaker conjugate base (A-).
True
Which equation do you use to find the pH of a buffer zone?
Henderson-Hasselbach
procedure for the analysis of nitrogen in organic compounds
Kjeldahl Nitrogen Analysis
use to standardize the acid/base titrant in a titration
Primary Standards
(EX: KHP standardization of NaOH)
True or False: At 1/2 Ve1, pH = pKa2.
True
True or False: At 1/2 Ve2, pH = pKa1.
True
when moles of H+ equals moles of OH-
Equivalence Point
True or False: EDTA has a 1:1 stoichiometric ratio with any metal complex.
True
What are the different types of EDTA titrations?
Direct, Indirect, Back, Masking, Displacement
a species used to stabilize a metal ion and keep that metal in solution; binds loosely enough to be displaced by a titrant
Auxiliary Complexing Agent
solute equilibrates between the mobile phase and sites on the surface of the stationary phase
Adsorption Chromatography
(NOTE: stronger adsorption means slower movement)
different sized solutes penetrate pores in the stationary phase to different extents; larger solutes elute first
Size/Molecular Exclusion Chromatography
ions in the mobile phase are attracted to counterions covalently attached to the stationary phase
Ion-Exchange Chromatography
solute in the mobile phase is attracted to specific groups covalently attached to the stationary phase
Affinity Chromatography
solute equilibrates between the mobile phase and a film of liquid attached to the stationary phase
Partition Chromatography
What does A represent in the van Deemter equation?
Multiple Flow Paths/Eddy Diffusion
What does B/ux represent in the van Deemter equation?
Longitudinal Diffusion
What does Cux represent in the van Deemter equation?
Mass Transfer
a form of chromatography in which the mobile phase is a gas
Gas Chromatography
What do narrower columns mean?
higher resolution, shorter analysis time, greater sensitivity, lower sample capacity, higher pressure
What happens as film thickness increases?
retention time increases, resolution increases, bleeding increases
a device that detects substances eluted from a gas chromatography column by measuring changes in the thermal conductivity of the gas stream
Thermal Conductivity Detector
a detector in which solute is burned in a mixture of H2 and air to produce CHO+ ions and electrons in the flame
Flame Ionization Detector
a detector that is particularly sensitive to compounds with halogen atoms, nitro groups, and other groups with high electron affinity; high electron affinity analytes capture some of the electrons and reduce the detector current
Electron Capture Detector
True or False: When concerning the stationary phase, like dissolves like.
True
What do smaller particle sizes mean?
a larger number of theoretical plates
a chromatographic technique using very small stationary phase particles and high pressure to force solvent through the column
High-Performance Liquid Chromatography (HPLC)
Formula for E(cell)
E(cell) = E(cathode) - E(anode)
Where does oxidation occur?
Anode
Where does reduction occur?
Cathode
When is a cell galvanic/voltaic?
when E(cell) > 0 or positive; means spontaneous
Absorption Spectrophotometer
light source > monochromator > sample > detector
Emission Spectrophotometer
light source > monochromator > sample >
monochromator > detector
Radiation Energy Transition Types:
Microwave
Rotational
Radiation Energy Transition Types:
Infrared
Vibrational
Radiation Energy Transition Types:
UV/VIS
Electronic
Radiation Energy Transition Types:
X-Ray
Bond Breaking and Ionization
Polymer Goals
purification, molecular weight, monomer/polymer ratio, rigidity, thermal stability, toxicity analysis
Polymer Challenges
inhomogeneous properties, high viscosity, soluble only in organic solvent
methods used in polymer analysis
FTIR, Raman, UV/VIS, NMR, Gel Permeation Chromatography, Mass Spectroscopy, Thermal Gravimetric Analysis, Differential Scanning Calorimetry, Dynamic Light Scattering
