Question:
How many grams of Oxygen are in 100 g of water? What percentage of the mass of water is oxygen?
Answer :
Given that -
Molar mass of water = 18 g/mol
Molar mass of oxygen = 16 g/mol
Step 1) :
Mass of Oxygen in given amount of water is calculated as :
Mass of Oxygen =
100.g × [(16g/mol)/(18g/mol)] × [(1 mol O)/(1mol H2O)]
= 88.89 gram Oxygen.
So, 88.89 g of oxygen are there in 100.0 g of water.
Step 2) :
Now, percentage of the mass of oxygen in water is can calculated as:
= (Mass of Oxygen) /(100.0g H2O) × 100%
= (88.89 g O) / (100.0 g H2O) × 100%
= 88.89 % Oxygen.
Percentage of the mass of oxygen in water is 88.89%.