Question

Question 1: In appreciation of you taking my General Chemistry class I want to gift each of you One Billion Gold (Au) atoms. I want you to calculate how much it will cost me?Given: We have 40 students in the class. Gold is $1200per ounce; 1 ounce = 28 g; Atomic weight of Au = 197.

Question 2:Suppose I decide to give One Billion Gold atoms to each and every human being on earth. How much that will cost me? Assume the world population 5 billion.

Answer 1

q.no : 1

No of mol of gold for each atom = (1*10^9)/(6.023*10^23)

= 1.66*10^(-15) mol

for 40 students

= 1.66*10^(-15)*40

   = 6.641*10^(-14) mol

mass of gold = 6.641*10^(-14)*197

     = 1.31*10^-11 grams

28 grams   = 1200 dolar

1.31*10^(-11) grams cost = 1200 * (1.31*10^(-11))

   = 1.572*10^(-8) dolar

Q.2 :

for 5 billion students

= 1.66*10^(-15)*5*1*10^9

   = 8.3*10^(-6) mol

   mass of gold = 8.3*10^(-6)*197

      = 0.001635 grams

28 grams   = 1200 dolar

0.001635 grams of gold = 1200*0.001635

= 1.962 dolar