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Re: % (by mass) of Gold in Gold/Silver alloy

Submitted by curlygirly999 on Sat, 08/22/2009 - 22:16

I am stuck on this question and was hoping for someone to help me with the steps necessary for solving it on my own. My instructor never covered this!

A piece of jewelry weighs 9.35g with a volume of 0.654cm3. Assume the metal is an alloy of gold and silver with densities of 19.3 g/cm3 and 10.5 g/cm3 respectively. Assume no volume change when gold ans silver are mixed. Calculate the percent by mass of gold in the jewelry.

Thanks.


Calculate the density of the sample from the mass and volume data.

Assign x as the percent (as a decimal) of Au.  That makes the percent of Ag equal to 1-x.

Density of sample (calculated above) = x (density of Au (given) )  +  (1-x)(density of Ag (given))
        Solve the equation above for x.


Well thank you very much. Those steps were invaluable. *phew* Thanks again, hopefully I can get the rest of the questions on my own now.