## Chemistry and Chemical Reactivity (9th Edition)

Published by Cengage Learning

# Chapter 1 Basic Concepts of Chemistry - Study Questions - Page 21d: 47

a) Au, Ag, Cu b) 1337 K c) No, it's osmium. d) 4.185 g e) 688,800 g; $35.88 million #### Work Step by Step a) According to the text, 18- carat gold is made of gold (Au - sixth period), silver ( Ag - fifth period) and copper (Cu - fourth period, ALL three from group 11). b)$T(K) = T(°C) +273$by definition For$T(°C)= 1064°C$:$T(K)=1337 K$c) The most dense element is Osmium (Os) with 22.59 g/cm$^3$. d) Since 18-carat means 75% of pure gold:$5.58g \times 0.75= 4.185 g$e) Each ring loses 6.15 mg of gold per year, each couple has two rings and in the US there are 56 million couples; thus, the total gold loss is:$6.15\ mg \times \dfrac{1\ g}{1000\ mg}\times2\times 56,000,000 = 688,800\ g$Since gold costs$\1620 per troy ounce and one troy ounce equals 31.1 g, the total value loss: $688,800\ g\times \dfrac{1\ t.o.}{31.1\ g} \times \dfrac{\$ 1620}{1\ t.o.}= \$35.88\ million$

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