Question

Calculate the following:
(a)Number of moles in 12g of oxygen gas
(b) Mass of 0.5 moles of water molecules.

Answer 1

Dear student. Number of moles = Given mass/Molar mass (1) Molar mass of O2 = 32 g/mol ​Number of moles in 12 g O2 gas = 12/32 = 0.375 moles 2.)The chemical formula of water is H2O and its molar mass i.e. the mass of one mole or 6.022 X 1023 molecules of water is 18g. Thus, mass of one mole of water = 18g mass of 0.5 moles of water = (18 X 0.5)g = 9g Thus, the mass of 0.5 moles of water is 9g. Regards