10. Calculate the number of molecules of sulphur (S,) presell ll16 g o

1.	10. Calculate the number of molecules of sulphur (S,) presell ll16 g of solid sulphur.I1. Calculate the number of aluminium ions present in 0.051 gof aluminium oxide.(Hint: The mass of an ion is the same as that of an atom ofthe same element. Atomic mass of Al27 u)
Answer» 1 mole of aluminium oxide (Al2O3) = 227 + 3 16 = 102 g i.e., 102 g of Al2O3 = 6.022 * 10^23 molecules of Al2O3 Then, 0.051 g of Al2O3 contains = = 3.011 * 10^20 molecules of Al2O3 The number of aluminium ions (Al3+) present in one molecule of aluminium oxide is 2. Therefore, the number of aluminium ions (Al3+) present in 3.011 * 10^20 molecules (0.051 g ) of aluminium oxide (Al2O3) = 2 * 3.011 * 10^20 = 6.022 * 10^20

10. Calculate the number of molecules of sulphur (S,) presell ll16 g of solid sulphur.I1. Calculate the number of aluminium ions present in 0.051 gof aluminium oxide.(Hint: The mass of an ion is the same as that of an atom ofthe same element. Atomic mass of Al27 u)

Answer»

1 mole of aluminium oxide (Al2O3) = 2*27 + 3 * 16

= 102 g

i.e., 102 g of Al2O3 = 6.022 * 10^23 molecules of Al2O3

Then, 0.051 g of Al2O3 contains =

= 3.011 * 10^20 molecules of Al2O3

The number of aluminium ions (Al3+) present in one molecule of aluminium oxide is 2.

Therefore, the number of aluminium ions (Al3+) present in 3.011 * 10^20 molecules (0.051 g ) of aluminium oxide (Al2O3) = 2 * 3.011 * 10^20

= 6.022 * 10^20