Answer:
4.1843 x 10²² atoms Pt
Step-by-step explanation:
To find the number of platinum (Pt) atoms, you need to (1) convert grams to moles (using the atomic mass) and then (2) convert moles to atoms (using Avogadro's number). It is important to arrange the conversions in a way that allows for the cancellation of units. The final answer should have 5 sig figs to match the amount of sig figs in the given value (13.555).
(Step 1)
Atomic Mass (Pt): 195.08 g/mol
13.555 grams Pt 1 mole
--------------------------- x ------------------------- = 0.069484 moles Pt
195.08 grams
(Step 2)
Avogadro's Number:
6.022 x 10²³ atoms = 1 mole
0.069484 moles Pt 6.022 x 10²³ atoms
--------------------------------- x --------------------------------- = 4.1843 x 10²² atoms Pt
1 mole