Question

What mass of the compound CrO3 (M=100.0) contains 4.5x10^23 Oxygen atoms?
Please show your steps.

Answer 1

CrO₃ << we've a 3 oxygen atoms

1 mole of CrO₃ = 100g
in 1 oxygen atoms we've a 6,022*10²³ atoms (Avogadro constant)

in 100g of CrO₃-----------------3*6,022*10²³ oxygen atoms
in x g of CrO₃ ------------------ 4,5*10²³ oxygen atoms
x = 24,91g of CrO₃