Question

In an experiment, potassium chlorate decomposed according to the following chemical equation:

2KClO3 → 2KCl + 3O2

(Molar mass of KClO3 = 122.5 g/mol; KCl = 74.55 g/mol; O2 = 31.998 g/mol)

If the mass of KCl produced was 180 grams, which of the following calculations can be used to determine the mass of potassium chlorate decomposed?

Answer 1

mole concept is applied

Moles = given mass over molar mass

Balance the equation:
2KCIO₃: 2KCI + 30₂

(1 mole = Molar mass of the molecule)
(2 mole = 2 x Molar mass)

—> if 2 moles of KCI is produced then 2 moles of 2KCIO₃ should be decomposed

2 x Molar mass of KCI is produced = 2 x
Molar mass of 2KCIO₃ is decomposed

Molar mass of KCI = 74.55 g/mol(given)
Molar mass of 2KCIO₃ = 122.5 g/
mol(given)

2 × 74.55 gram KCI = 2 × 122.5 gram of 2KCIO₃

—>
1 gram of KCI = 2 × 122.5 over 2 × 74.55
of 2KCIO₃

180 gram of KCI will produce:
2×132.5 over 2 x 74.65 × 180 of 2KCIO₃

= 295.77 gram