the crucible is not fired, as the procedure suggests, but had retained some impurities from previous use (or it could be oily smudges from fingers). The mass of the "dirty" crucible is recorded. However the impurities are burned off the experiment. Will the mass of final product be too high, too low, or unchanged as a rsult of this technique error? explain

Question

the crucible is not fired, as the procedure suggests, but had retained some impurities from previous use (or it could be oily smudges from fingers). The mass of the "dirty" crucible is recorded. However the impurities are burned off the experiment.  Will the mass of final product be too high,  too low, or unchanged as a rsult of this technique error? explain

anonymous · Answer

crucible + dirt = 3.2grams
place on scale, press tare then the crucible weights 0.000g
you add 2grams of (X) = now the weight is 2grams according to the scale.
you don't care what the weight of the crucible is after you tare the scale. 

unless,

you put the crucible on the scale, tare it out to 0.000
Add 2 grams of X
heat it up
empty it out
reweigh the crucible to verify total grams of X added
then yes you will think you put more in than you really did.

abb0t · Answer

If impurities remain, then mass will increase. It is similar to packing a bag with only pants, but if your pants have stuff inside them, maybe a wallet, or a rock, or mayb even socks, then the mass will increase.

anonymous · Answer

Thank you! (: