Answer:
2.62 × 10^23 molecules
Explanation:
We are required to determine the number of molecules in 20.0 g of NO₂
We are going to use the following simple steps;
Step 1: Calculate the number of moles of NO₂
Moles = Mass ÷ Molar mass
Molar mass of NO₂ = 46.0 g/mol
Therefore;
Moles of NO₂ = 20 g ÷ 46.0 g/mol
= 0.435 moles
Step 2: Calculate the number of molecules
We need to know, 1 mole of a gas contains molecules equivalent to the Avogadro's number, 6.022 × 10^23.
Therefore; 1 mole of NO₂ = 6.022 × 10^23 molecules
Number of molecules = Moles × Avogadro's number
= 0.435 moles × 6.022 × 10^23 molecules/mole
= 2.62 × 10^23 molecules
Thus, there are 2.62 × 10^23 molecules in 20 g of NO₂
