. What is the mass of:
(a) 0.2 mole of oxygen atoms?
(b) 0.5 mole of water molecules?
Answer: The mass is as follows:
(a) Mass of 1 mole of oxygen atoms = 16u, hence it weighs 16g
Mass of 0.2 moles of oxygen atoms = 0.2 x 16 = 3.2u
(b) Mass of 1 mole of water molecules = 18u, hence it weighs 18g
Mass of 0.5 moles of water molecules = 0.5 x 18 = 9u