Analytical Chemistry
Chapters 2, 6, 10, and 14
by Andrew DiMuro
Chapter 2
Chemicals and Apparatus:
Putting the Tools to Work
The Tools of the Trade
Chapter 2: A reference guide?
Many of the tools used in the
analytical chemistry lab are listed and
described in chapter two. If at any time,
you need to find out what instrument you
are holding in your hand, go to your
handy-dandy reference guide in chapter
two.
Be accurate and precise
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All glassware must be free of cracks
All materials must be cleaned with water,
soapy water, then twice with deionized water
to ensure that all impurities are removed
Measurements using the analytical balance
must be weighed to the nearest milligram
Primary standards must be calibrated to four
decimal places
The Lab Notebook
For experiments, the lab notebook is
essential for recording data.
All data must be recorded straight into
the notebook
All sections must be properly labeled
Experiment must be dated (bring
flowers)
Cross out incorrect data
Do not remove pages from the notebook
Chapter 6
Gravimetric Methods of Analysis
Errors
Errors occur all of the time in the lab.
Not every experiment can be reproduced
with 100% accuracy. If an experiment
contains four trails, one might be different
from the other three.
Statistics
Mean - the average value of a set of data.
The standard deviation curve, a.k.a. the
Gaussian curve, is used to plot how far
away a data point is from the mean.
Equation y = e^-(x-µ)2/2ó2
ó2pi
Significant Figures
Another source of error is the incorrect
use of significant figures and rounding off.
Answers
should be rounded off based on
the number with the smallest amount of
significant figures in the equation
Chapter 10
Theory of Neutralization Titrations
Mass-Balance Equations
These equations involve the relationships
among equilibria of various species
The equations are used to balance
concentrations
Charge-Balance Equations
Electrolytic solutions seek to be
electrically neutral.
In solution, the molar concentration of
positive charge equals the molar
concentration of negative charge, or:
# mol/L +charge = # mol/L -charge
Mass Balance Equations
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Steps for solving multiple equilibria
problems
write balanced
chemical equations
set up equation
for unknown quantity
write equilibrium
constant expressions
write mass
balance
expressions
write charge
balance equation
count # of equations and
# of unknowns
is # equations
> or = # unknowns
STOP
no
problem unsolvable
yes
make suitable
approximations
solve equations
for
unknown
were
approximations
valid?
go back to 7
no
and try
again
yes
problem
solved
The chart outlined in the previous slide is
extremely useful in solving equilibria
problems
Chapter 14
Complex-Formation Titrations
Applying neutralization
titrations
Concentrations of analytes, that are either
acids or bases, can be determined by
neutralization titrations.
Most titrations are completed with water
as the solvent, but some organic acids are
not soluble in water
Ligands
Ligands are ions or molecules that donate
a pair of electrons to a metal atom or
cation from their unshared pair of
electrons.
The complex forms a covalent bond by
sharing these pairs of electrons.