Hi Pilar,
We've done the same prac here. Two things I've done to reduce the risk are: 1) Measure out the NaOH into individual flasks, and the teacher dispenses it from the fume cupboard(then no-one is messing around with strong NaOH and measuring cylinders, except me!), & 2) I have purchased a set of individual electric hotplates @ approx $25 ea for pracs like these, as well as when we have to heat alcohols.
![Thumbsup :thumbup:](./images/smilies/thumbsup.gif)
The hotplates are available from discount shops like Crazy Clarks etc. I actually negotiated a good deal with an electrical store that gives a big discount if you pay cash. They wanted to look "community minded" and we gave them a "Thank you" on letterhead - a win/win situation.
Apart from that, the results of this prac seem to be largely dependent on whether the moon is in the 4th quarter of Venus, and whether students' auras were in tune with their environment on that day! In other words, our results ranged from lovely, identifiable hard soap, to a form of soft handwash, to complete disaster. Sounds like lots of student experiments doesn't it?
Good Luck. K
![Cool 8-)](./images/smilies/cool.gif)