Question

What is the mass of `3.7 * 10^20` molecules of Rubidium Phosphate? `(Rb_3PO_4)`

Answer 1

Approximately `2.16*10^-1 \ "g"=0.216 \ "g"`

Explanation:

We first convert to moles of `Rb_3PO_4`. In a mole of a substance, there'll be `6.02*10^23` units of that substance.

So, here we have:

`(3.7*10^20color(red)cancelcolor(black)(Rb_3PO_4 \ "molecules"))/(6.02*10^23color(red)cancelcolor(black)(Rb_3PO_4 \ "molecules")"/mol")~~6.15*10^-4 \ "mol"`

Now to find the mass, we multiply by its molar mass, which is `351.3748 \ "g/mol"`.

`6.15*10^-4color(red)cancelcolor(black)"mol"*(351.3748 \ "g")/(color(red)cancelcolor(black)"mol")~~2.16*10^-1 \ "g"`