TOOLS FOR THE LABORATORY

TOOLS FOR THE LABORATORY

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/safety.html

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.edu/Classes/Exton/Misc/reports.html

LABORATORY BALANCES analytical balances ± 0.1 mg top-loading balances ± 0.01 to ± 0.001 g

MASS SUBSTITUTION WEIGHING

BOUYANCY CORRECTION Learn about this in p-chem

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

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! try this tutorial http://antoine.fsu.umd.edu/cgi-bin/senese/tutorials/sigfig/IC.cgi TD means to deliver

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

MICROPIPETS fixed and adjustable volumes color coded tips

MICROPIPETS

FILTRATION Gooch crucible with fritted disk membrane filter apparatus analytical filter types

FILTRATION photomicrograph of glass fiber filter photomicrograph of controlled pore size track etched filter

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

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

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)

SAMPLE DISSOLUTION Fuse in muffle furnace to form a solid solution (flux) with eutectic electrolytes: LiCl, K2CO3, NaOH, Li2B4O7 Dissolve residue in dilute HNO3

MICROWAVE DISSOLUTION chemical dissolution microwave oven vessel must have pressure relief capability inert microwave vessel assembly

MICROWAVE DISSOLUTION Parr microwave acid dissolution “bombs” Parr microwave dissolution “bombs”

TOOLS FOR THE LABORATORY