Australia's Science Forum

Hi All,
We are about to do a prac from Science Aspects Book1 page 249 "How does temperature affect viscosity"
It asks for

* glass tubes that are 50cm or taller and
* engine oil that needs to be heated to 80 degrees and
* marbles or ball bearings which are dropped into the oil column..

The idea is that marbles are timed to see how long it takes for them to drop through the column of oil, at 2 different temperatures.
Does anyone have ideas for sourcing glass tubes, or perhaps polycarbonate tubing that can withstand oil at 80 degrees suitable for dropping marbles into?
Does anyone have any suggestions for the most suitable grade of engine oil to use?
Any other ideas or suggestions are most welcome.

Many thanks
Teresa

We did this many moons ago and it was quite fun (but veeeeery messy!) and I used old burettes which, of course, were then useless for anything else. Wide bore glass tubing could also be used and I buy that from hardware shops or QStores; I'm pretty sure any of the usual science suppliers have it. Plenty of newspaper is a must, but we had good success. I don't think we heated the oil too high and we used different grades of oils.
Good luck
LIZ

I cut some glass tubing and put stopper in each end remove stopper from 1 end fill with cheap motor oil from super market to about 1 cm from top put stopper in and invert, with stopwatch time air bubble travelling to top.
No danger of steel ball bearings hitting bottom and breaking glass and you can use alot smaller bore tubing, less oil to make a mess

We use cheap shampoo for our year 8 viscosity pracs. lots of bubbles in the clean up but better than oil. safe to heat, but goes "off" after heating. Can't be used a second time. We also use the old burettes, the plastic one when the taps crack are really great just pull the tap part out and a nice graduated plastic tube, rubber stoppers in one end very easy clean up when finished.

bernie

Hi, at my school for this prac I have made up several 30cm long tubes and sealed the ends with clear silicon and have filled each tube with different oils.
One has cooking oil, motor oil, parrafin oil, etc. I have left enough space in the tubes to form a bubble.
So all the students do is have some stop watches and turn them upside down and time how long it takes for the bubble to rise.
I am interested to read that prac that is mentioned and will at first chance.
Trish.

Here I used standard class tubing 6mm diameter (4 cut to same length about 20cm)sealed one end off with Silastic and filled them with acetone, water, glycol(antifreeze) and glycerol, to 1.5 - 2 cm from top and sealed off with Silastic. These I taped parralell to a piece of board(using double sided tape behind each tube and normal sticky tape across all to secure. Very successful except for the acetone eventually evaporated (after some time, not immediately). If I can find a way of sealing the acetone off I will fix the tubes permanently to the board. They are inverted and the bubble is timed to demonstrate viscosity.

We too used old burrettes - tend to be the broken ones
a good use for them really