Consider a piece of gold jewelry that weighs 9.35 g and has a volume of 0.690 cm3 . The jewelry contains only gold and silver, which have densities of 19.3 g/cm3 and 10.5 g/cm3, respectively. If the total volume of the jewelry is the sum of the volumes of the gold and silver that it contains, calculate the percentage of gold (by mass) in the jewelry.

1 answer

If there are g grams of gold, then add up the volumes (mass/density):

g/19.3 + (9.35-g)/10.5 = 0.690
g = 4.6
So, the % mass of gold is

4.62/9.35 = 0.49 = 49%