TOOLS FOR THE LABORATORY

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TOOLS FOR THE LABORATORY
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SAFETY IN THE LABORATORY
Working in a chemical laboratory requires that
the individual be primarily responsible for his
or her own safety. If you are not sure ask for
help. College of Charleston laboratory safety
policy page http//www.cofc.edu/chem/safety/sa
fety.html
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LABORATORY NOTEBOOKS
? Use a book with permanently bound pages. Spiral
or comb bound books are not suitable for use in
court. Make all entries with ink. ? Write a brief
outline of your lab procedure before you come to
lab to increase your working efficiency,
especially equations. Record notes from the
pre-lab lecture, especially procedure
modifications and sample calculations. ? Record
all observations in the notebook. Do not write
numbers on loose paper. Take your notebook into
the balance room. ? All charts or computer
printouts pertinent to the project should be
permanently put in the notebook with your
initials and date. ? Make tables of the test data
if possible. ? Don't erase. Cross out errors and
make a new entry. Entries should not be changed
at a later date. Make a new entry, pointing out
any change. ? More information
http//www.snco.com/instruction.htm http//www.
darbylaw.com/note.html http//chemlabs.uoregon.ed
u/Classes/Exton/Misc/reports.html
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LABORATORY BALANCES
analytical balances 0.1 mg
top-loading balances 0.01 to 0.001 g
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MASS SUBSTITUTION WEIGHING
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BOUYANCY CORRECTION
Learn about this in p-chem
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BURETS
Capacity Subdivision Tolerance Read mL mL
mL mL 10 0.05 0.02 0.005 25 0.1 0.03 0.01
50 0.1 0.05 0.01 100 0.2 0.10 0.02
Class A
read the bottom of the meniscus consistently at
the top and bottom of the buret measure volume
by difference
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VOLUMETRIC PIPETS
Capacity Tolerance mL mL 1 0.006 5
0.01 10 0.02 25 0.03 50 0.05 100
0.08
Class A
always use a pipet bulb never your mouth!
TD means to deliver
try this tutorial http//antoine.fsu.umd.edu/cgi-
bin/senese/tutorials/sigfig/IC.cgi
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VOLUMETRIC FLASKS
Capacity Tolerance mL mL 5 0.02 10 0.02 25 0
.03 50 0.05 100 0.08 250 0.12 500 0.20 1000 0
.30
Class A
allow flask to reach room temperature before
filling to mark
TC means to contain
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MICROPIPETS
fixed and adjustable volumes color coded tips
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MICROPIPETS
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FILTRATION
Gooch crucible with fritted disk
membrane filter apparatus
analytical filter types
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FILTRATION
photomicrograph of glass fiber filter
photomicrograph of controlled pore size track
etched filter
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GLASSWARE CALIBRATION
An empty weighing bottle had a mass of 10.283 g.
After adding water from a 25 mL pipet, the mass
was 35.225 g. If the lab temperature was 23 C,
what was the volume of water delivered by the
pipet?
TABLE 2-4 T C mL/g 15 1.0020 16 1.0021 17
1.0023 18 1.0025 19 1.0027 20 1.0029 21 1.0031
22 1.0033 23 1.0035 24 1.0038 25 1.0040
value from Table 2-4
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GLASSWARE CALIBRATION
What mass of water is required to be delivered at
15 C from a 10 mL pipet so that the volume of
the pipet is exactly 10.00 mL?
value from Table 2-4
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SAMPLE DISSOLUTION
? Increase surface area to increase reaction
rate ? Heat solution to increase reaction rate ?
Active metals dissolve in strong mineral acids
HCl, HNO3, HF, H3PO4, H2SO4 M(s) n H (aq)
Mn (aq) n/2 H2 (g) ? Form volatile products in
dissolution CO32-(aq) 2 H(aq) H2CO3(aq)
H2O(l) CO2(g) ? Form complex ions in
dissolution Fe(s) ? Fe3 (aq) 6 CN- (aq)
Fe(CN)63 (aq)
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SAMPLE DISSOLUTION
Fuse in muffle furnace to form a solid solution
(flux) with eutectic electrolytes LiCl, K2CO3,
NaOH, Li2B4O7 Dissolve residue in dilute HNO3
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MICROWAVE DISSOLUTION
chemical dissolution microwave oven
vessel must have pressure relief capability
inert microwave vessel assembly
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MICROWAVE DISSOLUTION
Parr microwave acid dissolution bombs
Parr microwave dissolution bombs