Question

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?

Answer 1

`"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!