LABORATORY HINTS AND TIPS

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LABORATORY HINTS AND TIPS

• Presented by Mary K. Moore, Eastman Chemical
  Company

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How Cold do you want to go?

• When low temperatures are required for collecting
  gas samples, doing a reaction, or collecting
  volatile gas from a distillation, Try the
  following salt-ice mixtures
• 30g KCl in 100g ice water will cool to -10oC
• 33g NaCl in 100g ice water will cool to -21oC
• 85g MgCl2 in 100g ice water will cool to -34oC
• 143g CaCl2.6H2O in 100g ice water will cool to
  -55oC

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Salt and Ice water not cold enough?

• Dry ice proved an easy way to reach very low
  temperatures. Use crushed dry ice and mix with
  ethanol, acetone, isopropyl alcohol, or xylene.
  When using ethanol or acetone you can reach
  temperatures as low as -72oC.

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Trouble placing rubber tubing on glassware or
metal?

• Add a small amount of acetone in the end of your
  rubber tubing before placing it on the glassware
  or metal. This helps fuse the tubing to the
  object.
• Use water and Kevlar gloves for inserting glass
  tubing and thermometers into rubber stoppers.

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Have you "burped" liquid when using a funnel to
add liquids to a sample jar?

• Unfold a paper clip and place it between the
  funnel and the container. This will allow air to
  escape.

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Pouring Liquids from Beakers

• Hold a glass stirring rod against the pouring lip
  of the beaker
• Tilt the container, allowing liquid to flow
  around the stirring rod, the liquid will be
  guided into the beaker.

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Have you ever had to clean up a mercury spill?

• When using mercury filled monometers in the fume
  hoods, place a polyethylene tub under the
  monometer to collect the mercury if the monometer
  breaks.

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Weighing out liquids

• Pour approximate liquid amount into an Erlenmeyer
  flask or a beaker.
• Use a disposable pipette for final measuring.

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Have you ever had trouble with excel
spreadsheets? Try color coding.
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Do you add to much grease on stopcocks?

• Put grease in a 50ml plastic syringe. This way
  you can add a small amount of grease on the
  connection. After using, relieve pressure by
  pulling back on the plunger. Store for further
  use.
• Use a paper towel and get a small amount of
  grease on the towel and rub on the glass-ground
  connection.

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Some Ideas for balances.

• Keep the space beside the balance clear, allowing
  you to weigh your objects and place them to the
  side.
• Keep a pad of paper and a pen next to your
  balances to write weights down.

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Weighing Solids

• When weighing dry samples, place a bi-fold towel
  under the container. If the sample spills, the
  towel will catch the solids. After weighing,
  pick-up the towel from each side and bring them
  together, forming a "V". You now have a built-in
  funnel.

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Problems with Crystallization?

• One of the following techniques or some
  combination of them may be helpful
• Scratch the side of the beaker with a glass
  stirring rod. Use a freshly cut piece with an up
  and down motion.
• "Seed" with the original material, by dropping
  some into the cooled flask.
• Cool the solution in a freezer or freezing
  mixture.
• Add crumbs of dry ice.
• Let stand for a long period of time.
• Change solvent system

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Cutting small diameter glass tubing

• Always use cut resistant gloves!
• Scratch the glass rod with a three-cornered file
  or glass cutter, use considerable pressure,
  however, do not saw.
• Add a drop of water to the filed section of the
  glass rod.
• Using little force, pull back on the glass rod
  and push thumbs outward quickly to break the
  glass.

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Waste Disposal

• Segregate wastes in clearly marked containers to
  avoid possible chemical reactions. Consider the
  possibility of spontaneous reactions, explosions,
  and fire.
• Minimize waste

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Volumetric Flask

• Use a thin gauge wire to attach the stopper to
  your volumetric flask. This will prevent you from
  losing the stopper.

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CONTRIBUTORS

• John Engelman, SC Johnson
• Daphne Eggers, Eastman Chemical Company
• Juanelle Lambert, Eastman Chemical Company
• Janet Smith, Dow Corning Corporation
• Doug Chaffin, Eastman Chemical Company
• Andrew Vetter, Eastman Chemical Company
• John Moncier, Eastman Chemical Company
• Amy Nave, Eastman Chemical Company
• Vicki Bledsoe, Eastman Chemical Company