Answer:
6.36 x 10²⁰ atoms
Explanation:
To find the number of atoms in the P₂O₅ sample, you need to (1) convert grams to moles (using the molar mass of P₂O₅) 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 3 sig figs like the given value (0.150 g = 3 sig figs).
Atomic Mass (P) = 30.97 g/mol
Atomic Mass (O) = 16.00 g/mol
Molar Mass (P₂O₅): 2(30.97 g/mol) + 5(16.00 g/mol)
Molar Mass (P₂O₅): 141.94 g/mol
Avogadro's Number:
6.022 x 10²³ atoms = 1 mole
0.150 g P₂O₅ 1 mole 6.022 x 10²³ atoms
----------------------- x ---------------- x ------------------------------- = 6.36 x 10²⁰ atoms
141.94 g 1 mole
