Australia's Science Forum

Anyone help me out please?

We have a yr 8 prac that uses plaster of paris, add so many drops of water, and time the temperature change every minute.

Then we want the students to take the raw data and graph it.

BUT the problem is that we havent been getting satisfactory temperature changes in the prac.

Wondering if anyone has another prac that demonstrates the same chemical energy (exothermic) released.

Or even if you could get me some raw data from that or a similar prac, that the students can just go straight to the results & graphing?

Possible to post it here... (or send to me ?)

How about using a strip of zinc, copper or magnesium in some hydrochloric acid? Measure the temperature of the acid then add the metal and maybe measure temp every 30 seconds?

There is a year 12 prac for calorimetry that we did just recently that tested exothermic reactions. The three reactions were:
0.2g of magnesium in 100mL 1.0M HCl
50mL 0.1M HCl and 50mL 0.1M NaOH
100mL water and 3g KNO₃.

All three gave a pretty good temperature increases in the insulated calorimeter. We didn't try it without insulating so I don't know how it would go in a simple beaker.

Just be careful if you use HCl and Magnesium as this produces Hydrogen gas.

thank you both for these.

You could do something similar to you Plaster prac but with NaOH? But you would have to do aN RA on it i guess

Yes, I could.
I have been thinking thought re the Ca, Mg & Na OH. The idea is to have less water at the beginning , and more later on. But with both those pracs I will have to modify to add the water all at once..or else risk hazardous situtaion...
then log temp rise as the reaction progresses.

Thanks

Perhaps you could do marble chips (calcium carbonate) instead then and use HCl as the liquid.