Wireless Temperature Contest Winner
Stephen Jacobs of St. Francis Xavier Secondary School is the winner of our contest for a classroom set (qty 10) of PASCO’s award winning wireless temperature sensors.
Please join us in congratulating Stephen!
Stephen’s submission was to use the PASCO Wireless Temperature Sensors to demonstrate the of Enthalpy of Hydration. We are looking forward to posting the results of his experiment in a future blog.
“After introducing the concept of enthalpy of hydration to my students, I give my students a small sample of cement (~ 10g), they add distilled water from a dropper (counting drops) or a buret (monitoring volume) and determine the ratio of water to cement sufficient create a mix that when placed onto a trowel, will remain as the trowel is rotated 90 degrees.
From this students learn the ideal ratio of water to cement.
Next, students are given a small quantity of cement (sufficient to fill a 400 mL beaker), and by ratio, the ideal amount of water is added slowly and the reactants are mixed with wooden paint sticks. The thermometer is either coated with “Vaseline”/stopcock grease or “Saranwrap” and is placed into the center of the mixture in the beaker. The temperature is monitored over time. The cement cures with 24 hrs at which point the thermometer is removed.
Extensions…
- My students have coated the inside of used paper towel rolls with “Vaseline” and have made large quantities of cement to stuff inside these prepared rolls. My students team up with Physics students to design different concrete compositions (fine sand, coarse sand, gravel (sorted by mesh size), and “rebar” (consisting of iron wire (available at TSC stores). After chem students have measured the enthalpies of hydration, the physics students design experiments looking at the physics of cantilever beams…and test the beams to the point of failure.
- Instead of cement, I would combine calcium hydroxide and sand and have students measure the same reaction inside an improvised calorimeter.
- The topic extends far beyond the normal curriculum as my students learn about restoration work of historic structures and the fact that cement was invented just before the time of the Romans.”