empirical formula problem

[iLoveDivX]

i'm doing a chem lab and the experiment deals with burning magnesium ribbon. Here are my data.

mass of crucible + lid 20.218
mass of crucible, lid and sample 20.389
mass of sample 0.162
mass of crucible, lid and product 20.4932
mass of product 0.274

From these data, I'm supposed to figure out the empircal formula of Magnesium Oxide. I got it to be Mg2O which i think is wrong cause i think the correct answer is MgO. Is my data wrong or what?

 

[minendo]

was the original sample just magnesium

 

[iLoveDivX]

yes

 

[minendo]

i think i may be doing it wrong but i come up with mg3o2

 

[minendo]

i have a feeling the data may be wrong because the empirical formula of Magnesium oxide is MgO.

Link

 

[Capn]

I'm getting Mg0 (approximately)

.162/24.3 = .0067
(.274-.162)/16 = 0.007

0.0067:0.007 ~ 1:1

 

[iLoveDivX]

oh, i see. you divided by 16. i divided by 32 cause i was confusing myself with the O2 stuff.

hey capn, here's the second part to this lab. It's calcium oxide

Mass of sample = .959
mass of product = .879

 

[iLoveDivX]

any reply to the calcium oxide? it's due tomorrow and i'm sleepy

 

[Capn]

what do you do to the calcium oxide?

 

[iLoveDivX]

it's the exact same as the magnesium oxide. in this case, i burn the calcium.

 

[Capn]

you burn the calcium sample, yielding some sort of calcium oxide, am I reading that right? If that's right, then it doesn't make any sense that the product has a lower mass than the initial calcium sample.

 

[iLoveDivX]

it's a decomposition reaction.

 

[Capn]

heh, I'm sorry I'm being retarded here for a second.

Calcium Oxide yields Calcium ? Is that your experiment?

Please give me a little more information here, it's been a while since I had chemistry.

 

[iLoveDivX]

Calcium heated in Oxygen yielding Calcium Oxide. It's a decomposition reaction therefore getting a lesser mass of a product than the reactant.

 

[iLoveDivX]

it's the exact same thing as the Magnesium + Oxygen yielding Magnesium Oxide.

I did the Calcium Oxide calculation and I got Ca5O which is wrong.

 

[Capn]

Ca -> CaO is not a decomposition reaction. Do you mean the decomposition of Calcium Carbonate by heating to Calcium Oxide?? That would yield Calcium Oxide.

 

[Dangermouse33]

You in Chem142?