[Incendiary]

We did an experiment where KClO3 was heated in a crucible until it decomposed to KCl and O2...

However, before putting in the KClO3, the empty crucible was heated to prevent excess moisture from remaining in the crucible. Is this because the KCLO3 has the tendency to absorb water?


How would excess moisture affect the KCLO3 reaction during heating (the amount of oxygen given off)?

[Borek]

Have you weighted the crucible? If so, weighting it wet would be a source of obvious problems.

Could be wet chlorate may splutter if roasted wet.

[Incendiary]

Have you weighted the crucible? If so, weighting it wet would be a source of obvious problems.

How would that affect it? Please explain?!

[Borek]

This is a common problem in experiments that require you to weight crucible before and after roasting. After roasting crucible is usually dry, but before it may be wet - and if it is, its mass will be not that of dry crucible, but of crucible plus some amount of water. If you try to find mass of the substance left after roasting subtracting initial mass form the final mass, your result wil be off by the mass of water that was not removed before the roasting.