Question

Potassium chlorate decomposes according the following BALANCED equation.

Answer 1

Answer:

12.9 g O₂

Explanation:

To find the mass of oxygen gas produced, you need to (1) convert grams KClO₃ to moles KClO₃ (via molar mass from periodic table values), then (2) convert moles KClO₃ to moles O₂ (via mole-to-mole ratio from reaction coefficients), and then (3) convert moles O₂ to grams O₂ (via molar mass). It is important to arrange the conversions/ratios in a way that allows for the cancellation of units (the desired unit should be in the numerator). The final answer should have 3 sig figs to match the given value (33.0 g).

Molar Mass (KClO₃): 39.098 g/mol + 35.45 g/mol + 3(15.998 g/mol)

Molar Mass (KClO₃): 122.542 g/mol

2 KClO₃ ---> 2 KCl + 3 O₂

Molar Mass (O₂): 2(15.998 g/mol)

Molar Mass (O₂): 31.996 g/mol

33.0 g KClO₃           1 mole                 3 moles O₂            31.996 g
--------------------  x  -------------------  x  -----------------------  x  ------------------  =
                               122.542 g          2 moles KClO₃            1 mole

=  12.9 g O₂