question_answer 21)

What is the mass of (a) 1 mole of nitrogen atoms? (b) 4 moles of aluminium atoms (atomic mass of aluminium = 27)? (c) 10 moles of sodium sulphite (Na2SO3)  ?  

Answer:

(a) Mass of nitrogen atom = number of moles x atomic mass                                       = 1 x 14 = 14 g   (b) Mass of aluminium atom = 4 x atomic mass = 4 x 27 = 108 g    (c) Mass of  Na2SO3 = 2 x 23 + 32 + 16 x 3 = 46 + 32 + 48 = 126 g 1 mole of  Na2SO3 = 126 g Therefore,  10 moles of Na2SO3 = (10 x 126) g = 1260 g