Saturday, December 17, 2005

Vague remembrances of chemistry

If I remember correctly, we (Joe, Jason and I) mixed potassium sulfate [K2SO4] and lead nitrate [Pb(NO3)2] in a water solution. Then lead sulfate [PbSO4] precipitated out of the solution (lead nitrate is one of the very few lead compounds that is soluble in water). We poured off the solution into shallow dishes and let the water evaporate on the windowsill. Voila! Potassium nitrate [KNO3] crystals.

K2SO4 + Pb(NO3)2 -> PbSO4 + 2KNO3

We never got to make the gunpowder, though. Mr. Rainey gave our potassium nitrate to one of the other science teachers to use in a class demonstration of some sort. We were kind of upset about that (who wouldn't be?), but were consoled (a little) by the fact that she said it worked as well as the supply-store stuff she had run out of.

Later,

2 people have spouted off:

Braddock said...

but its unpure because the lead sulfate won't evaporate with the water?

John said...
the lead sulfate precipitates out of solution as a solid. once it settles, the solution can be poured off, leaving the lead sulfate in the original test tube.
1/20/06, 5:09 PM