Precious metals are commonly measured in troy ounces. A troy ounce is equivalent to 31.1 g. How many moles are in a troy ounce of gold? How many moles are in a troy ounce of platinum? of silver?

1 Answer
Jun 4, 2016

Answer:

#"Number of moles"# #=# #"Mass"/"Molar Mass"#

Explanation:

The number of moles is a numerical unit. One mole of stuff unequivocally specifies #"Avogadro's Number"#, #N_A#, #6.022xx10^23#, individual items of that stuff.

Now the molar mass of gold is #196.97*g*mol^-1#. From where did I get that mass? Did I know it from memory? From where will YOU get it if you are asked to use it?

So #"Moles of gold"# #=# #(31.1*g)/(196.97*g*mol^-1)# #=# #?? mol#

And #"Moles of platinum"# #=# #(31.1*g)/(195.08*g*mol^-1)# #=# #?? mol#.

And #"Moles of silver"# #=# #(31.1*g)/(107.87*g*mol^-1)# #=# #?? mol#.

How do the individual numbers of platinum, silver, and gold compare in these quantities? Which quantity has the greatest monetary value?

On a personal level, I think only a really decadent society would continue to use such an absurd unit as a #"troy ounce"#. For God's sake!