you've measured the mass of some pennies that were minted before 1982, when they had a different composition than they do today. they were still made of zinc and copper, but in a diferent ratio. you've found that one penny has a mass of 3.1 grams, and has a volume of 0.35 cubic centimeters. find the mass of the copper in this penny...
2006-09-16 07:00:32 · 3 answers · asked by hey 3 in Education & Reference ➔ Homework Help
SG of Cu = 8.96
SG of Zn = 7.13 (at STP)
Assuming there are no impurities or other substances present, it should be easy to figure it out from here.
If your 0.35 cc penny was pure copper it would have a mass of 3.12 g. If it was pure Zn it would have a mass of 2.50 g. So now you know that the penny will be at least 50% Cu, and you will have to calculate the ratio of Cu to Zn to come up with the mass of 3.1 g, and then apply that ratio to 3.1 to figure out the mass of the Cu. That's a fairly simple math homework problem that you should be able to figure out.
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"Give a person a fish and s/he can eat for a day. Teach a person how to fish and s/he can eat for a lifetime."
2006-09-16 07:13:19 · answer #1 · answered by minefinder 7 · 0⤊ 1⤋
do a search in Yahoo answers -- someone else just asked almost the exact same question
2006-09-16 14:10:32 · answer #2 · answered by Anonymous · 1⤊ 1⤋
There isnt enuf infomation to answer the problem.
2006-09-16 14:10:10 · answer #3 · answered by MarijuanaMan 2 · 0⤊ 1⤋