Chemistry HL Design prac

        When a polar liquid such as water is flowing in a presence of a charged rod, the liquid tend to bend towards the rod. This is because the rod will either be positively or negatively charged, and the dipoles of the polar molecule will be attracted to the charged rod. The charge on the rod is determined by the material which is used to rub against it, however, it does not matter whether the rod is positively or negatively charged because either way, the opposite dipoles of the polar molecule will be attracted towards it, causing the flow of the liquid to bend towards the charged rod.

Defining Independent and Dependent Variables

Controlling Variables

Table 1 – Variables and Method of control

Materials and Equipments List:

• 50 mL Burette
• 20cm x 15cm silk cloth
• 1cm diameter glass rod
• Distilled water
• 200 mL Beaker
• A4 Grid paper with increments of 1mm
• Protractor with increments of 0.5 degrees
• Retort Stand
• clamp
• Pen
• Ruler
• Sticky tape
• Stop watch

Method

1. Attach the clamp to the retort stand.
2. Fill the burette with distilled water to approx 1cm from the top and attach it to the clamp
3. Draw a straight line on the grid paper with a ruler and sticky tape it to the bottom of the burette, lining up the line on the paper exactly with the flow of the water coming out of the burette.
4. Also Draw a line 90 degrees towards the line if the flowing water but stopping at 0.5 cm from the line. This line will be where the charged glass rod will be placed
5. Also mark the origin (the tip of the burette, where the water comes out) on the grid paper
6. Place the 200 mL beaker under the burette and let the water run down
7. Start the timer on the stopwatch and simultaneously, begin rubbing the glass rod against the piece of silk
8. Stop the stop watch at 10 seconds and immediately place the charged rod as close as possible to the line drawn on the grid paper
9. Mark the angle of deflection of the water on the grid paper
10. Wait 1 minute until the rod is completely uncharged
11. Repeat steps 6 – 9
12. Repeat the experiment from steps 6 – 10, changing the time rubbing the glass rod against the silk cloth by 20, 30, 40, 50 and 60 seconds.
13. Remove the grid paper and line up all the points of the deflected water to the origin
14. Measure the angles with a protractor and record the results into the table below
15. Pack up the experiment

Table 2 – Raw data table

Bibliography

1. Columbia University Press (1978-1979). New Illustrated Columbia Encyclopaedia
2. Neuss, Geoffrey (2007). Chemistry Course Companion. Oxford: Oxford University Press.
4. Department of Physics and Physical Science, University of Nebrasky, Kearney Falling Water