Question

Determine the mass of CO₂ that contains 7.92 x 10¹⁸ O atoms.

Answer 1

ANSWER:

One mole or 44g of CO₂ molecules contain 6.022 X 10²³ CO₂ molecules

1 molecule of CO₂ contain 2 atoms of Oxygen

Therefore 44g (1 mole) of CO₂ contain 2 X 6.022 X 10²³ = 12.044 X 10²³ Oxygen atoms

Equating the two

12.044 X 10²³ Oxygen atoms = 44g CO₂

Or

1 Oxygen atom = 44 / 12.044 X 10²³ = 3.65 X 10^-23 g CO₂

It mean 1 Oxygen atom is present in 3.65 X 10^-23 g of CO₂

Therefore

7.92 x 10¹⁸ atoms of oxygen will be present in 3.65 X 10^-23 X 7.92 x 10¹⁸ = 28.93 X 10^-5 g of CO₂