Ionic & Covalent conduction

Dr.Roo

Best dressed trans' tech in the dept. X
I get that covalent compounds are usually insulators, but I'm hoping to do a demo where, when solid the substance doesn't conduct (electricity) but when molten it does.
Anyone know which material does this, please?
 
Apart for some exotic polymers potentially, I cant think that any covalent compound will conduct
 
I think the only common covalent bonded substances that conduct are graphite and silicon.
Melting to conduct would be ionic bonding usually, but you can find a salt that melts at a lower temperature than NaCl, that is high temperature work!
Glass is an insulator cold but can conduct when hot.
 
I get that covalent compounds are usually insulators, but I'm hoping to do a demo where, when solid the substance doesn't conduct (electricity) but when molten it does.
Anyone know which material does this, please?

We use lead bromide if I recall, has a relatively low melting point and fits the criteria. Make sure to do it in the fume hood though as it releases bromine vapours.
 
We set up a electrolysis circuit with electrodes and a volt meter attached too. We get the students to put the electrodes in water and obviously no voltage is shown. We then get them to put the electrodes in sodium chloride or potassium chloride, again no voltage. Finally we ask them to put the salt into the water and they then get reading on the voltmeter
 
Another vote for lead bromide (in a crucible)

If you want to really blow their minds (the teacher - kids don't care) a glass rod will conduct electricity if you get it hot enough..
 
Top