Question

Tin (Sn) exists in Earth's crust as SnO2. Calculate the percent composition by mass of Sn and O in SnO2.

Answer 1

Answer:

Sn = 78.77%

O = 21.23%

Explanation:

The atomic mass of Sn = 118.71 g/mol

The atomic mass of O = 16 g/mol

The molar mass of SnO₂ = atomic mass of Sn + 2 X atomic mass of O

The molar mass of SnO₂= 150.71

Now, in each mole of SnO₂ there is one mole of Sn and two moles of O

The mass of Sn in 150.71 g of SnO₂ = 118.71

Percentage of Sn in 150.71 g of SnO₂ = $\frac{MassofSnX100}{massofSnO_{2} }$

% of Sn = $\frac{118.71X100}{150.71}=78.77$%.

Rest will be O = 100-78.77 = 21.23%

Answer 2

Atomic mass of Sn = 118.71 amu. Atomic mass of O = 15.99 amu,
∴ percent composition by mass of Sn =
   atomic mass of Sn x 100/molar mass of SnO2 = 118.71 x 100/150.69
                                                                             = 78.77%
percent composition by mass of O = 15.99 x 100/150.69 = 10.61%