In an experiment, zinc chlorate decomposed according to the following chemical equation. Zn(ClO3)2 → ZnCl2 + O2 (Molar mass of Zn(ClO3)2 = 232.29 g/mol; ZnCl2 = 136.286 g/mol; O2 = 31.998 g/mol) If the mass of zinc chlorate was 150 grams, which of the following calculations can be used to determine the mass of oxygen gas formed?

The mass of oxygen gas : = 61.98 g

Given

Reaction

Zn(ClO3)2 → ZnCl2 + O2

The mass of zinc chlorate was 150 grams

Required

The mass of oxygen gas

Solution

Balanced equation :

Zn(ClO₃)₂ → ZnCl₂ + 3O₂

mol of Zn(ClO₃)₂ :

= mass : MW

= 150 : 232.29 g/mol

= 0.6457

From equation, mol ratio of Zn(ClO₃)₂ → ZnCl₂ : O₂ = 1 : 3, so mol O₂ :

= 3/1 x mol  Zn(ClO₃)₂

= 3/1 x 0.6457

= 1.937

Mass of  O₂ :

= mol x MW

= 1.93  x 31.998 g/mol

= 61.98 g

Or we can use equation :

= (150 x 3 x 31.998) : (232.29 x 1) grams

= 14399.1 : 232.29

= 61.98 g

neutrons are in the middle of the atom and the electrons, which are much smaller.