CHEMISTRY 1211 UA Avogadros Number Lab

CH110 Pre-Labrevised Spring 2020
AVOGADRO’S NUMBER
1.
The initial volume in a graduated cylinder was 2.05 mL. A student added 100 drops of an oleic
acid solution to the graduated cylinder and the final volume was 3.03 mL.
(a) What is the volume of one drop from the dropper? Show full calculation, with units and sig
figs.
The solution used was 0.50 % (by volume) oleic acid.
(b) What is the volume of oleic acid contained in one drop ? (Remember 0.50% = 0.0050)
Show full calculation, with units and sig figs.
One of the above drops was used to create a film with a surface area of 137 cm2. Assume the
film is a very wide but short cylinder, therefore
volume of this film = (surface area) x (thickness)
Note: The film is created by only the oleic acid in the drop, the remainder of the drop is ethanol,
which dissolves into the water. Also remember that 1 mL = 1 cm3.
(c) Use the volume from 1b and the surface area given to calculate the thickness of the film in
cm. Show full calculation, with units and sig figs.
2.
Describe the procedure for the experiment. This could be in an outline format or a flow chart
format or paragraph format. It should not be copied directly from the manual. (This should be
between ½ and one page, you may use the back of the page)
3.
Briefly discuss all safety precautions related to this experiment. (chemical and equipment
related). See additional information regarding chemical handling and waste treatment on next
page.
CH 110
DETERMINATION OF AVOGADRO’S NUMBER
Chemical Handling and Waste Treatment
Normal laboratory safety practices must be followed at all times. SDS sheets are available in
the laboratory or on-line at hartford.edu/SDS; then go to Sciences; Chemistry; Binder.HTM &
search alphabetically.
The oleic acid solution is ethanol based which makes it flammable. Do not use near sparks or
flames.
The lycopodium powder is a very fine solid which makes it flammable, do not use near sparks
or flames. Avoid inhalation of the powder it can irritate the nose and lungs. If any of the
powder is spilled, wipe the bench top with a wet sponge or paper towel after the experiment is
completed. Also wipe the floor if any of the powder is spilled because it can make the floor
slippery.
Skin contact does not pose any serious danger, however (as with all chemicals) rinse any
exposed areas with cold tap water immediately.
Disposal of all reagents is as follows: rinse down the drain with lots of cold tap water.