Question

How many total atoms are in 0.360 g of P2O5?

Compound: 1 2 3

Formula: XY6 XY? XY?

Mass of Y per gram of X 2.82g 1.41g 0.94g

what are the formulas of compounds 2 and 3?

Answer 1

1) How many total atoms are in 0.360 g of P2O5

moles of P2O5 = 0.360 / 142 = 2.54 x 10^-3

1 mole ---------------------> 6.023 x 10^23 molecules

2.54 x 10^-3 moles -----------> 6.023 x 10^23 molecules x 2.54 x 10^-3 = 1.527 x 10^21 molecules

1.527 x 10^21 molecules = 1.527 x 10^21 x 7 atoms = 1.069 x 10^22 atoms

1.069 x 10^22 atoms ---------------------------> answer

2)

compound 2 : XY3

compound 3 formula : XY2

explanation :

use law of multiple propotion:

2.82 / 2 = 1.41 = half of Y

2.82 /3 = 0.94 = 1/3 time of Y