Charles Law

     Introduction: One of the variables that affects the volume of a gas is the
temperature of the gas and its surroundings. This volume-temperature
relationship is quantified in Charles’s law. The law states that as the
temperature of a gas decreases, the volume of the gas decreases proportionately.

An ideal gas at 273 K, for example would decrease in volume by 1/273 of its
original volume for each Celsius degree the temperature decreases. If the
temperature decreased sufficiently, the volume should decrease to zero. Real
gases, however, liquefy and solidify long before this theoretical limit, called
absolute zero, is reached. By using air as a sample of a real gas and limiting
the temperature range, it is possible to estimate the temperature that would
correspond to absolute zero. Materials Used: ? Apron ? Goggles
? Thermometer ? Hot Plate ? Paper Towel ? Thin Stem

Pipet ? (2) 400-mL Beakers Objectives: ? Demonstrate the
relationships between the temperature of a gas and its volume. ? Graph
the relationship. ? Estimate the temperature of absolute zero by
extrapolation. Procedure: ? Fill two 400-mL beakers half full with tap
water. ? Begin heating the water in one beaker to a temperature that is

10*C above room temperature. ? Fill a thin stem pipet completely with
room temperature water. To make sure the pipet is filled, first draw in as much
water as possible. Then, holding the pipet by the bulb with the stem pointing
upward, squeeze the bulb slightly to eject any air left in the bulb and stem.

Keeping this pressure on the bulb, insert the tip of the stem into the water.

Release the pressure on the bulb, and the pipet will fill completely. ?

Dispense the water from the pipet counting the total number of drops it takes to
empty the pipet. ? Record the room temperature and the number of drops.
? Stop heating the water when a temperature 10*C above the room
temperature is reached. ? Holding the thin stem pipet by the stem,
immerse the bulb in the warm water. ? Hold the pipet in the warm water
for a few minutes so that the air in the pipet reaches the temperature of the
water. ? Pinch the stem of the pipet to seal off the bulb. Place the bulb
in the other beaker of water which is at room temperature. ? Still
pinching the stem, immerse the entire pipet, including the stem, in the water,
release the stem underwater. A small amount of water should be drawn into the
pipet. This water is equal in volume to the amount of gas lost when the pipet
bulb was heated and the air inside it expanded. ? Remove the pipet from
the water bath. Dry the outside of the pipet, with the paper towel. Expel the
water, counting the number of drops of water that were drawn into the pipet.
? Add the number of drops to the initial volume noted. Record the total
volume and the temperature of the warm water bath. ? Dry the inside of
the pipet, by drawing in the air and then releasing the bulb several times.
? Repeat from the 6th to the 13th step at a temperature that is 10*C
above the previous trial. ? Continue this procedure until the water
temperature is approximately 75*C. ? Record all results. Data And

Observations: Temperature/Volume Changes Of Air Temperature (*C) Total Volume
(Drops) 19 134 29 138 39 140 49 160 59 169 69 178 Conclusions: 1- 2- 3- Errors

And Possible Improvements: ? Possible errors could occur while counting
the drops, people can either lose count, or too many drops will be let out
instead of single drops. To improve this patience and tolerance are a must,
hurrying will only cause the person to re-start from the beginning. ?

Errors could also occur while taking the temperature of the warm water, if the
hot plate is turned off, the beaker will obviously cool down a few degrees and
so this might affect the results. An idea to improve this would be setting the
hot plate on a moderate heat so that the same heat temperature can be stable
throughout the procedures. ? Errors could occur if the tip of the pipet
is not pinched properly, this will result in the false number of drops getting
drawn into it. To improve this one must make sure the whole tip is pinched and
that there is no space for any air to enter or escape. ? Errors could
occur if the number of minutes in which the bulb is immersed in the warm water
is different. This might have a few effects on the results and number of drops.

To improve this either make sure you set a stop watch or give each procedure the
same exact time to immerse the bulb.