1. A compound made of two elements, iridium (Ir) and oxygen (O), was produced in a lab by heating iridium while exposed to air. The following data was collected:

Mass of crucible: 38.26 g
Mass of crucible and iridium: 39.52 g
Mass of crucible and iridium oxide: 39.73 g

Show, or explain, your calculations as you determine the empirical formula of the compound.

And what's a crucible XS

Question

1. A compound made of two elements, iridium (Ir) and oxygen (O), was produced in a lab by heating iridium while exposed to air. The following data was collected:

Mass of crucible: 38.26 g
Mass of crucible and iridium: 39.52 g
Mass of crucible and iridium oxide: 39.73 g

Show, or explain, your calculations as you determine the empirical formula of the compound.

And what's a crucible XS

anonymous · Answer

First calculate the mass of iridium (Ir) : I make this to be 1.26g After oxidation the mass is .21g more. The atomic weight of Ir is 192g so the amount here is 6.56 millimoles. The increase in mass is 0.21g on oxidation and assuming only oxygen reacted with the iridium then this means that 13 millimoles of O reacted. So the empirical formula should reflect the fact that there's twice as much oxygen in the compound as Ir.

I'm sorry but I can't help with the crucible excess.

aaronq · Answer

he didn't mean crucible xss, it's just an emoticon.. 
a crucible is a container (usually small) made of ceramic used to heat substances.

anonymous · Answer

Thanks aaronq - I guess the crucible is something for heating metals or other substances in - I think they can be big in foundries where molten metal is poured into molds but mostly they are small ceramic heat resistant vessels.