Answer: 1.74g Pt
Step-by-step explanation:
This is a unit conversion problem, and we will be converting from atoms of Pt to mol Pt to g Pt, using Avogadro's constant (6.022 x 10²³ atoms/mol) and platinum's molecular weight (195.1g Pt/1 mol Pt).
I wrote it two different ways in case the fractions were a bit difficult to read. :)
5.36 x 10²¹ Pt atoms (
)(
) = 1.74g Pt
5.36 x 10²¹ Pt atoms (1 mol Pt/6.022 x 10²³ Pt atoms)(195.1g Pt/1 mol Pt) = 1.74g Pt
Our given value has three significant figures (5.36, so the 10²¹ doesn't count), so our final answer will have three significant figures as well.
I hope this helps! :)