There is a 10.0 grams necklace made of 18K gold. K, karat, is a measurement of the fineness (or purity of gold by Jeweler and gold dealers. Compared with 24K (pure gold), 18K means that the mass percent of gold is 18K/24k = 0.75 (or 75 wt%, we treat it as an exact number here). In another word, that necklace contains 75% gold by mass. If the international gold price today is $1323 (US) per troy ounce, and one troy ounce equals 31.103 grams, solve the following two questions:
(a) How many gold atoms are contained in this necklace?
(b) Neglecting the price/cost of the other metals (25 wt%, usually silver and other metals by mass) present in the 18K gold, find the value/price of this necklace according to its gold content.
(c) Since density of gold is higher than that of other metals, do you think the volume percent of gold in this piece is higher, or equal, or lower than 75 v% (volume percent)?
