Quant Exam 1 Flashcards
identification of what chemical constituents are present in a substance; identity of a compound
qualitative analysis
measurement of how much of a chemical substance is present; numerical answers
quantitative analysis
step one of chemical analysis
formulating the question - translating general questions into specific questions
step two of chemical analysis
selecting analytical procedures - doing a literature search
step three of chemical analysis
sampling - selecting representative materials to be measured
sample/material composition is the same everywhere
homogeneous
sample/material composition differs from region to region
heterogeneous
step four of chemical analysis
sample preparation - converting the sample into a suitable form
step five of chemical analysis
analysis - repeating measurements, applying different analytical methods
step six of chemical analysis
reporting and interpreting
step seven of chemical analysis
drawing conclusions
substance being measured or detected; also called “measured”
analyte
a solution whose composition is known by virtue of the way 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 precipitation
supernatant - also called “supernate”
a portion of a substance
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
a complete transfer
quantitative transfer
a homogenous mixture of two or more substances
solution
the minor species in a solution
solute
the major species in a solution
solvent
formula for molarity (M)
moles solute / liters solution
formula for molality (m)
moles solute / kilograms solvent
formula for weight percent (% wt)
(grams solute / grams solution) x 100
formula for parts per million (ppm)
milligrams solute / liters solution
chemical analysis based on weighing the final product
gravimetric analysis
Avogadro’s Number
6.022 x 10^23
formula for dilution
M1V1 = M2V2
how close together a set of measurements are; reproducibility
precision
how close a measurement is to the true/accepted value; nearness to the truth
accuracy
True or False: In addition/subtraction, the number of significant figures is determined by the number with the fewest decimal places.
T
True or False: In multiplication/division, the number of significant figures is determined by the factor with the smallest number of digits.
T
True or False: In logarithms, the number of significant figures determines the number of decimal places.
T
True or False: In antilogs, the number of decimal places determines the number of significant figures.
T
a built-in error, consistent, reproducible; in principle, detectable and correctable
systematic error
from uncontrollable variables in the measurement; inconsistent error value; can be reduced by repeated trials, but cannot be completely eliminated
random error
expresses the margin of uncertainty associated with a measurement
absolute uncertainty
compares the sizes of the absolute uncertainty with the size of its associated measurements
relative uncertainty
formula for relative uncertainty
absolute uncertainty / magnitude of measurement
formula for percent relative uncertainty
(absolute uncertainty / magnitude of measurement) x 100
True or False: The number of significant figures in the answer is limited by the number of decimal places in the uncertainty.
T
True or False: Random error can be expressed as the standard deviation/standard deviation of the mean/confidence interval.
T
True or False: Random errors in arithmetic processes propagate through calculations.
T
analyze known samples/certified reference materials, analyze blank samples, use different analytical methods to measure the same quantity, round-robin experiments
ways to detect systematic error
formula for relative standard deviation/coefficient of variation
(standard deviation / mean) x 100
the absolute value of the highest value minus the lowest value
range
True or False: When given an even number of data points, the median is the average of the two middle values.
T
True or False: When finding the confidence interval, the degree of freedom is the number of samples minus one.
T
EXCEL command for finding the mean
= AVERAGE ( : )
EXCEL command for finding the standard deviation
= STDEV ( : )
EXCEL command for finding the number of samples
= COUNT ( : )
replicate measurements of a sample made by a single analytical technique are compared to an accepted value
case one
comparing replicate measurements of a sample measured by two analytical techniques or samples created from two methods measured by one analytical technique
case two
multiple samples are measured by two different analytical techniques and the results are compared
case three
True or False: For case one, if the known value does not lie within the 95% confidence interval range, then the methods give different results.
T
calculated F value < table F value
the difference in standard deviations is not significant; use the s pooled formula to find t
calculated F value > table F value
the difference in standard deviations is significant; use the regular t formula
calculated t value < table t value
not significantly different mean values
calculated t value > table t value
significantly different mean values
calculated G value > table G value
questionable value can be discarded
calculated G value < table G value
questionable value cannot be discarded
True or False: When constructing a standard/calibration curve, the blank value should be subtracted from the measured values.
T - called corrected values
True or False: Concentrations of pure solids/liquids/solvents are omitted from the equilibrium constant formula because they are unity.
T
reverse reaction equilibrium constant calculation
K’ = 1 / K
added equilibrium constant calculation
K3 = K1 x K2
if a system is subjected to a change/disturbance, the direction in which the system proceeds back to equilibrium will attempt to offset the change
Le Chatelier’s Principle
Q < K (Le Chatelier’s)
the system will shift to the right until Q = K
Q > K (Le Chatelier’s)
the system will shift to the left until Q = K
True or False: Heat is a reactant in an endothermic reaction. (H > 0)
T
True or False: Heat is a product in an exothermic reaction. (H < 0)
T
(+) G, K < 1
disfavored reaction
(-) G, K > 1
favored reaction
the equilibrium constant for the reaction in which a solid salt dissolves to give its constituent ions in solution
solubility product
Q > Ksp (precipitation)
a precipitate will be formed
Q < Ksp (precipitation)
a precipitate will not be formed
a salt is less soluble if one of its ions is already present in the solution
common ion effect
True or False: A smaller Ksp value means a more soluble salt.
T
