Question

What is the mass of 4.92×1021 platinum atoms?

Answer 1

If 195g Pt ----- contains -------- 6,02×10²³
so x ----- contains -------- 4,92×10²¹


`x=(4,92*10^(21)*195g)/(6,02*10^(23))\approx 195,4*10^(-2)g=1,954g`

Answer 2

1.593 grams is the mass of
`4.92* 10^(21)` platinum atoms.

Step-by-step explanation:

`N=n* N_A`

`m=n* M`

Where:

N = Number of particles / atoms/ molecules

n = Number of moles

m = mass of sample

M = Atomic mass

`N_A=6.022* 10^(23) mol^(-1)` = Avogadro's number

We have:

Atoms of platinum = N =
`4.92 * 10^(21)`

Moles of platinum = n =?

`n=(N)/(N_A)=(4.92* 10^(21))/(6.022* 10^(23) mol^(-1))`

n = 0.008170 moles

Mass of N platinum atoms = m

Atomic mass of the platinum atom = m = 195 g/mol

`m=0.008170 mol* 195 g/mol=1.593 g`

1.593 grams is the mass of
`4.92* 10^(21)` platinum atoms.