Density and units

[Invincible-disa]

Gold is alloyed with other metals to increase its hardness in making jewelry. Consider a piece of gold jewelry that has a mass of 9.85g and has a volume of 0.675cc. The jewelry contains only gold and silver that have densities 19.3g/cc and 10.5g/cc respectively. Assuming that the total volume of the jewelry is the sum of the volumes of the gold and silver that it contains, calculate the percent of gold ( by mass) in the jewelry.

How do I solve this problem?

[IRstuff]

On 9/6/2003 6:37:46 AM, Invincible wrote:
>Gold is alloyed with other
>metals to increase its
>hardness in making jewelry.
>Consider a piece of gold
>jewelry that has a mass of
>9.85g and has a volume of
>0.675cc. The jewelry contains
>only gold and silver that have
>densities 19.3g/cc and
>10.5g/cc respectively.
>Assuming that the total volume
>of the jewelry is the sum of
>the volumes of the gold and
>silver that it contains,
>calculate the percent of gold
>( by mass) in the jewelry.
>
>How do I solve this problem?

You have the total volume, call it V, and you know that a portion, call it p, is gold and the remainder V-p, is silver. So,
dens_gold*p+(V-p)*dens_silver=total_mass
solve for p, then calculate the total mass of gold, then calculate the percentage of the total mass.


TTFN,
Eden