Which has more atoms, 50 g of aluminium or 50 g of iron? Illustrate your answer with the help of calculations.

Question

Which has more atoms, 50 g of aluminium or 50 g of iron? Illustrate your answer with the help of calculations. (Atomic masses: Al = 27 u; Fe = 56 u)

Philoid · Accepted Answer

Atomic mass of Al = 27u

1 mole of aluminium weighing 27g contains N = 6.022 x 10²³ atoms of Al

So, 50g of Al contains = 50 × N(6.022 × 1023)/27 atoms of Al = 11 × 10²³ atoms of Al

Atomic mass of Fe = 56 u

1 mole of iron weighing 56g contains N = 6.022 × 10²³ atoms of Fe

So, 50g of Fe contains = 50 × N(6.022 × 10²³)/56 atoms of Fe = 5 × 10²³ atoms of Fe

Thus, 50g of Al has more no. of atoms as compared to 50g of Fe. This is because Aluminium has a smaller atomic mass and is lighter.