How many atoms are in .405g of P2O5

Answer 1

To find the number of atoms in a substance, we first need to find the number of MOLES of substance that we have. We will then use Avogadro's number (6.022x10²³) to find the number of molecules, and finally we will find the number of atoms

The molar mass of P₂O₅ = 141.84 g / mole.

Moles of P₂O₅ in 0.405 g = 0.405 g x 1 mole / 141.84 g = 2.855x10^-3 MOLES P₂O₅

Next, we can calculate the number of P₂O₅ molecules that we have...

2.855x10^-3 MOLES P₂O₅ x 6.022x10²³ molecules / mole = 1.719x10²¹ molecules of P₂O₅

Finally, we can now calculate the total number of atoms present, noting that each molecule of P₂O₅ contains 2 atoms of P and 5 atoms of O, or a total of 7 atoms per molecule...

1.719x10²¹ molecules x 7 atoms / molecule = 1.20x10²² atoms