how many total atoms are in 0.450 grams of p2o5

Answer 1

Molar mass P₂O₅ (diphosphorous pentoxide) = 284 g / mole

moles P₂O₅ present = 0.450 g x 1 mol / 284 g = 0.001585 moles

molecules P₂O₅ = 0.001585 moles x 6.022x10²³ molecules / mole = 9.542x10²⁰ molecules

Since each molecule of P₂O₅ contains 2 P atoms and 5 O atoms (total of 7 atoms / molecule), ....

Number of atoms = 7 atoms / molecule x 9.542x10²⁰ molecules = 6.68x10²¹ atoms

Answer 2

Hi Carm R.,

p2o5 is not a chemical compound. When you get it into standard form (hint: element symbols have variously capital and lower case letters, which are not interchangable), add the atomic masses times their # of occurrences in the compound, use that to convert to moles, use Avogadro's relationship to find the answer, express to proper precision using scientific notation.

-- Q. Why is this the same number of atoms as in a piece of cake? (trick question --"Because the answer IS ......")

-- Cheers,

-- Mr. d.