Question

1. What is the mass in grams of a chlorine atom, Cl? 

2. What is the mass in grams of a hydrogen chloride, HCl? 

Answer 1

1. The atomic weight of Cl is 35.5 amu, so the molar mass of Cl is 35.5 g/mol. Dividing 35.5 g (per mole) by 6.023 x 10²³ gives the mass of one atom.  

2. The molecular weight of HCl equal to the atomic weight of H, plus the atomic weight of Cl, (ie) (1.01 + 35.5) amu = 36.5 amu. Therefore 1 mol of HCl contains 36.5 g HCl