Question

The number of atoms in a 158.4 g sample of CO2 gas at STP is:

1.277 x 1025 atoms

2.167 x 1024 atoms

6.502 x 1024 atoms

6.651 x 1024 atoms

Answer 1

6.502 x 10²⁴ atoms.

Step-by-step explanation:

First we convert 158.4 g of CO₂ into moles, using carbon dioxide's molar mass:

• 158.4 g ÷ 44 g/mol = 3.6 mol CO₂

Then we calculate how many CO₂ molecules are there in 3.6 moles, using Avogadro's number:

• 3.6 mol CO₂ * 6.023x10²³ molecules/mol = 2.168x10²⁴ CO₂ molecules

As there are 3 atoms per CO₂ molecule, we triple the number of CO₂ molecules in order to get the answer:

• 2.168x10²⁴ CO₂ molecules * 3 = 6.504x10²⁴ atoms

The closest answer is the third option, 6.502 x 10²⁴ atoms.