The air we breathe is approximately 21% oxygen. atypical breath has a volume of 450 ml. how many grams of O2 are in a breath of air

We breathe around an average of 500 ml of air in 1 normal (or relax) breathing. The lungs already have around 3 litres of reserve breathing. Since there is around 21% oxygen in air, we breathe in around 105 ml of Oxygen from the air. That is equal to around 0.14 g of Oxygen.