question_answer

  Find the number of atoms in 120 g of calcium and 120 g of iron. Which one has more number of atoms and how much is the  difference?                             [Atomic mass of Ca = 40 u, Fe = 56 u]

Answer:

                Molar mass of Ca= 40 g 40 g of Ca contains, number of atoms = 6.022 x1023 120 g of Ca contains, number of atoms = 18.066 x1023 = 1.8066 x 10 atoms Again molar mass of Fe = 56 g 56 g of Fe contains number of atoms = 6.022 x1023 120 g of Fe contains number of atoms  = 1.2904 x1024 atoms          Therefore, 120 g of calcium has more number  of atoms,                                   Difference = (1.8066 -1.2904) x 1024 = 5.162 x1023 atoms