# chemistry

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Before 1982 the US Mint cast penny coins from a copper and zinc mixture. If a 1980 penny weighs 3.051g and contains 0.153g zinc, what is the percent of copper in the coins?

• chemistry -

3.051 g = mass Cu + Zn
-0.153 g = mass Zn from the problem.
---------------
2.898 g Cu
%Cu = (2.898/3.051)*100 = ??

• chemistry -

94.99%

• chemistry -

gfh

• chemistry -

3.051 g Cu and Zn -0.153 g Zn=2.898 g Cu
After that: 2.898 g Cu/3.051 g Cu+Zn=0.94985 x 100%=94.99%

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