Unformatted text preview: rtion of a reagent to its original container. See if anybody
else at your bench, or in the lab, needs it. If not, give it to your instructor, who will look at you
in a forlorn and sullen manner but will appreciate that you did not put it back in the original
Returning unused portions of reagent greatly increase the odds of cross
contamination, that is, getting the reagent contaminated with an unwanted chemical.
NEVER pour a waste chemical in the drain, or put it in the garbage, unless otherwise
instructed to do so by your lab supervisor. Waste bottles will be provided. Always pour waste
into the appropriate and labeled waste bottle (reading the waste bottle label twice).
If you have glass stirring rods or glass tubes with sharp or jagged edges, fire polish them.
This means holding the sharp end in a Bunsen burner flame and rotating the rod or tube until a
bright orange flame begins to show on the end being heated. Continue to heat while rotating
another minute or so, effectively melting that end a little bit. Be SURE to let it cool
COMPLETELY before attempting to fire polish the other end. Dakota State University Page 13 of 232 Safety Guidelines General Chemistry I and II Lab Manual (9)
Many items (glass, metal, etc) look exactly the same HOT they do cool. Be VERY
careful whenever working with flames that ALL of your equipment (beakers, flasks, ring stands,
etc.) are cool before handling them.
(10) If you are inserting glass tubing into a rubber stopper, use the following technique to
avoid jamming a jagged piece of glass through your hand; (1) use glycerol or water to lubricate
either the end of the glass tubing being inserted, the hole in the stopper the tubing will be
inserted into, or both; (2) protect your hands by using a paper towel to hold both the glass tubing
as well as the rubber stopper; (3) hold the rubber stopper in such a way that the tubing cannot go
through the hole and into your palm (your fingers should actually curve, holding the edge of the
stopper, as if to make the letter "C"); (4) hold the glass tubing, also with your palm away from
the end, near the end being inserted into the rubber stopper; (5) insert the glass tubing with a
twisting motion; (6) clean up any excess glycerol; and (7) live your life free from scar tissue on
your palms that everybody for the rest of your life will ask about by saying "how did that
happen?", to which you will have to reply that you didn't listen to your dedicated and caring
(11) Improper heating of a test tube can result in the chemicals within the test tube shooting
out, possibly resulting in injury to anybody in the path. When heating a test tube, use the
following procedure; (1) unless directed otherwise, always place a few (five or six) boiling chips
in the test tube; (2) use a test tube clamp to hold the test tube; (3) hold the test tube at about a 45o
angle; (4) be sure the opening of the test tube is pointing away from anybody else (preferably
towards a wall in a low-traffic area of the lab); (5) NEVER heat the bottom of the test tube
(unless otherwise directed); instead heat the middle of the test tube just at the level of the liquid
in the test tube; (6) move the test tube horizontally back and forth across the flame to prevent the
liquid from heating too quickly; (7) should the liquid begin to overheat (heat too rapidly),
remove the test tube from...
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