Molecules and mole ratios

Question

How many molecules of O2 are required to produce 25.0 grams of NO2

Answer 1

2NO + O₂ ==> 2NO₂ ... balanced equation

Use dimensional analysis:

molar mass NO₂ = 46.01 g /mol

25.0 g NO₂ x 1 mol / 46.01 g x 1 mol O₂ / 2 mol NO₂ x 6.02x10²³ molecules / mol = 1.64x10²³molecules O₂ needed