quote:

Originally posted by VDub no...you're reading it wrong... The 60 and 40% are the copper content of the original 2 pieces... When they are melted, the resulting piece is 51% copper...

No, I'm not reading it wrong....the answer is above^^^^

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quote:

Originally posted by cammaxwell 400g x 51% = 204g of copper so... 2 pieces, one 220g and one 180g (220+180=400) 220g x 60% = 132g of copper 180g x 40% = 72g of cooper 132g + 72g = 204g of copper OR 51% of the 400g chunk

Yah that seems to work out doesn't it...

But where did you get the 220 and 180?

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quote:

Originally posted by chinamon chinamon is INCH MOAN. LOL so fitting.

200.8 and 199.2

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Last edited by Moral Hazard on Apr-26-2011 at 07:48

Billy told me...

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quote:

Originally posted by ChemEnhanced 200.8 and 199.2

See????

That's what I got.....

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quote:

Originally posted by chinamon chinamon is INCH MOAN. LOL so fitting.

quote:

Originally posted by VDub See???? That's what I got.....

now look in the back of the math book and get the answer

Copper = 204 Alloy = 196

60%copper (122.4) + 40%alloy (78.4) = 200.8

40%copper (81.6) + 60%alloy(117.6) = 199.2

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Last edited by Moral Hazard on Apr-26-2011 at 07:48

quote:

Originally posted by ChemEnhanced now look in the back of the math book and get the answer Copper = 204 Alloy = 196 60%copper (122.4) + 40%alloy (78.4) = 200.8 40%copper (81.6) + 60%alloy(117.6) = 199.2

What?

60% of 200.8 is 120.48......not 122.4?

....and 40% of 199.2 is 79.68....NOT 81.6?

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quote:

Originally posted by ChemEnhanced now look in the back of the math book and get the answer Copper = 204 Alloy = 196 60%copper (122.4) + 40%alloy (78.4) = 200.8 40%copper (81.6) + 60%alloy(117.6) = 199.2

You guys used the 204g for your calculation, but you have to use the ORIGINAL chuck for that....

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quote:

Originally posted by cammaxwell You guys used the 204g for your calculation, but you have to use the ORIGINAL chuck for that....

I have no idea if I am right....just playing with the numbers provided.

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Last edited by Moral Hazard on Apr-26-2011 at 07:48

The entire problem is incorrect as you would loose some weight in the melting process....therefore you would also need to determine how much weight is lost in the melting process.

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Last edited by Moral Hazard on Apr-26-2011 at 07:48

That really depends whether or not Billy is running an industrial assembly line. I mean, it's pretty unlikely that he has the equipment sitting around in his basement to melt and fuse copper with perfect efficiency and without introducing any impurities. So I'd have to assume he's working at a plant somewhere.

Assuming that, we still need to know if it's a clean room, like a fab, or a regular factory where the copper slabs have no doubt picked up all sorts of dirt, and the melting process probably leaves a copper residue behind.

Now, since the question explicitly states "the resulting piece", it also clearly suggests a freezing process. Does it go into a freezer, sealed, or is it just left sitting around until it solidifies? If memory serves, copper doesn't sublimate, but the impurities might at the right atmospheric temperature, which means that the resulting solid might actually be slightly more pure than the original liquid.

Finally, how is the determination of purity being made? It's easy enough to weigh the thing, but in order to determine the purity you usually have to melt it down or distill it, which seems to be a pointless exercise here after making the new alloy. And if Billy had to melt down the original two samples just to find out the purity, how can we be sure that he didn't lose some copper in that process, before he even started combining them? Are we assuming a specific loss rate here or are these ideal, perfect (i.e. imaginary) conditions?

More to the point, if Billy already has a scale, which he would have needed to weigh the final sample, why didn't he just weigh the original two samples in the first place instead of going through all this ridiculous hassle?

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