In the Science Lab experiment Viscosity of Liquids we examine the properties of different liquids beginning with a comparison of corn syrup and water. In Viscosity & Temperature we look at the behavior of a single liquid – corn syrup – at different temperatures.
Most liquids are more viscous at lower temperatures. The difference is very sharp with corn syrup. The experimental set up we use here is similar to that used in the first viscosity experiment with a few minor changes: we used steel balls instead of pebbles and we timed the descent between two specific marks on the graduated cylinder rather than from top to bottom.
There is PDF file of the experiment that you may want to download and duplicate for distribution to your students. It includes a chart that they may use to record the data they collect.
It is also a good idea to enter the data into a spreadsheet. You can compute the averages easily and use the data to produce graphs such as the the one below and the bar graph that appears on the results page.
We had an unanticipated result which we found interesting and which we mention in the "Try these ideas" section of the results page. It seems that the time it took for each drop in the cold corn syrup was less than the previous one. We didn't keep checking the temperature between trials, but our guess is that the corn syrup was warming up and becoming less viscous during the time it took us to conduct the five trials. In hot corn syrup, the time it took the ball to drop generally got longer from one trial to the next. We think this was because the corn syrup was cooling and becoming more viscous during the time we were conducting the tests.
Further Explorations
There is a group of liquids, called "non-newtonian liquids", that change viscosity when they are stirred, shaken, or otherwise agitated. These are described in two other Science Lab experiments: Ketchup: Thick or Thin? and Cornstarch and Water: Is it Liquid or Solid?
Another non-newtonian liquid is Visplex*, which is used in drilling fluid. It becomes more viscous when still and liquefies when agitated. This allows it to suspend rock cutting in a borehole when the drilling process is interrupted. To find out more, look at Drilling Fluid: Lifeblood of the Well in the @Schlumberger section of Science Watch.
* Mark of Schlumberger
