Calculate the percent composition of Potassium chlorate KClO₃.

Molecular mass of KClO₃

= K + Cl + 3O

= 39 + 35.5 + (3 x 16)

= 39 + 35.5 + 48

= 122.5 g

% of K = ?

Since, 122.5 g of KClO₃ contains 39 g of K

∴ 100 g of KClO₃ contains

= $\dfrac{39}{122.5}$ x 100

= 31.83%

Similarly, 122.5 g of KClO₃ contains 35.5 g of Cl

∴ 100 g of KClO₃ contains

= $\dfrac{35.5}{122.5}$ x 100

= 28.98%

And, 122.5 g of KClO₃ contains 48 g of O

∴ 100 g of KClO₃ contains

= $\dfrac{48}{122.5}$ x 100

= 39.18%