Chem 140 Experiment 1
Beran
Objectives;
1. Learn to operate the Bunsen burner
2. Learn to weigh objects using the analytical and top loading balances.
3. Determine the density of an insoluble object and a liquid.
Part A Bunsen Burner
1. Lighting the Burner
SAFETY CAUTION: USE THE PROCEDURE BELOW INSTEAD OF THE BOOK.
NOTE: Before attempting to light a Bunsen burner, make sure that you are successful in
generating sparks out of the striker. If you are not successful in getting the burner lit after
two attempts, TURN OFF THE GAS FROM THE GAS JET.
Bunsen burners are located in the metal ware drawer. Always check the rubber tubing for
holes. Most heating in your chemistry course is done with a gas burner. In this laboratory
you will use a burner of the Bunsen Type. The Bunsen burner has a gas needle valve at
the base of the burner to control the amount of gas and in that way, the size of the flame.
The burner also has an air inlet just above the gas inlet, which can be adjusted by
screwing or unscrewing the barrel of the burner. This adjustment determines the amount
of air mixes with the gas. The larger the air opening the hotter the flame becomes.
The fuel used for the burner is natural gas. You will find a natural gas jet at each work
area. Always be sure the gas jet is shut off completely when the burner is not lit.
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Close the gas needle valve of the burner (turn counter clockwise) at the bottom of
the burner.
Adjust the barrel of the burner so that you see an air opening.
Turn the gas jet 90 degrees. Adjust the gas needle valve of the burner clockwise
until you hear the gas.
Light the burner with a striker. Strikers are hanging on both ends of the table
sinks.
Adjust the air control to get a blue, nearly transparent flame.
Turn the gas jet off when finished with burner.
If the air inlet is closed and the gas is lit, the flame will be large and luminous. The light
is the radiation given off by the hot carbon particles that are burned only partially. This
luminous flame is not very hot and dangerously flimsy. This very cool flame type will
never be used in this lab. If the air control is adjusted so that air is mixed with the gas
before it gets to the flame, the flame will become less luminous, and finally blue. When
the air is adjusted correctly to give the hottest flame, it will look something as shown on
page 47 of your lab book. The inner cone of the flame is pale blue, and the outer cone is
pale violet. The inner cone contains the unburned gas that is hot enough to radiate light.
The hottest point is just above the inner cone.
Adjust the gas needle valve to increase or decrease the flame height. The air inlet can be
adjusted to larger opening for a hotter flame or to a smaller opening for a cooler flame.
2. Observing Flame Temperature Using a Wire Gauze
a. Crucible tongs, wire gauze are in the metal ware drawers at the South end of the labs.
b. Use extreme care when working with a luminous flame. Make sure that the flame is
not too tall.
3. Observing Flame Temperatures using the Melting Points of Metal.
a. The copper and aluminum wires and iron nails are on the North counter under the
Chem 140 sign.
Part B Laboratory Balances
Use the top loading balances for this part. There are no balance numbers. Leave this part
of the data sheet blank.
Part C Density
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Get your unknown solid from the stockroom. Transfer the unknown # label to
your data sheet. No credit for this portion will be received without the unknown
label.
Use the top loading balance for this part.
Note the modification to #1 below. The italic portions are the modifications.
1. Water-Insoluble Solid. A. Obtain an unknown solid and transfer the label to
your data sheet. Using the top loading balance tare the mass of a weighing boat,
place all the solid metal on the weighing boat, and measure its mass.
b. Half-fill a 50 mL graduated cylinder.
c. As written.
2. Liquid, Water. Use the analytical balance for this part.
a. The smallest beaker in your kit is the 50 mL beaker. Check-out a 5.00 mL
volumetric pipet and a green pump from the stockroom.
3. Liquid, Unknown. a. Dry the beaker and rinse the pipet with distilled water. Get
your unknown liquid from the stockroom and transfer the label to your data sheet.
b. As written
Have data sheet sign after competing each of the experiments.