Experiment n5: Recording data from gas pressure

Background information:
It is important that all materials made of glass in this experiment (the schlenk tube) should be dried in an oven before use. The schlenk tube or flask was invented by Wilhelm Schlenk. It comes equipped with a stopcock which allows the vessel to be filled with gases, mainly used for inert gases. Whatever gas that is inserted doesn't matter. The properties are the same for every gas because it is a general law in science.

Aim:
To observe the variability in gas pressure relating it to the temperature.

Variables:
Independent variable (x): The independent variable in this case will be the temperature (tºC).
Dependent variable (y): The dependent variable is the gas pressure, P(hPa).
Constant variable: There are many constant variables throughout the experiment, the most important ones are the gas volume and the gas mass.

Materials:
- Magnetic stirring
- Bunsen Burner
- Tripod
- Container
- Wooden planks
- Clamp
- Stand
- Gas pressure sensor
- Stirrer (magnetic pill)
- Lighter
- Blocks of ice
- Schlenk tube
- Water


Procedure:

1 - Set the whole mechanism up: elevate the magnetic stirring with the wooden planks the height of a bunsen burner and place the tripod underneath. Then, place the container on top, hold the schlenk tube with the clamp and stand and in the container (it is important that the tube cannot touch the base or any of the sides), and place the stirrer in the container as shown in image 1 -->
Also make sure that the gas pressure measurer is connected to both the schlenk tube and the computer to record the data.

2 - Pour enough water so that it covers the schlenk tube entirely. Not a single drop under.

3 - Place 3 blocks of ice and wait for the temperature to drop to its lowest. After this, turn on the bunsen burner to increase the temperature of the water in the container.

4 - For every 3ºC change in temperature, record data on the computer software and observe the change in the pressurised gas. It is important to note that when the 3º has appeared on screen, leave the bunsen burner off for a few seconds until the temperature is stabilised.

5 - Make a graph with the values you have obtained.

Results:
Our group has obtained accurate values and we know this by calculating the value of "R" squared of the graph obtained. Below is a graph showing our results with a line of best fit.

Bibliography:

http://www.youtube.com/watch?v=KW9EITxozzg
http://en.wikipedia.org/wiki/Schlenk_flask