When heated, KClO3 decomposes into KCl andO2. 2KClO3⟶2KCl+3O2 If this reaction produced 39.9 g KCl how many grams of O2 were produced?

Answer 1

Hi Lexie,

For this reaction, you need to convert grams of KCl to moles of KCl, using the molecular weight of KCl (39.10+35.45 = 74.55 g/mol). Then using the stoichiometric ratio (coefficients from the balanced chemical equation), you then convert moles of KCl to moles of O2 gas (2 to 3 ratio). Once in moles of O2, you use the molecular weight of oxygen (32.00 g/mol) to arrive at the final answer. Don't forget to leave your answer in 3 significant figures.

(39.9 g)/(74.55 g/mol) = 0.535 mol KCl

0.535 mol KCl * (3 mol O2/ 2 mol KCl) = 0.802 mol O2

0.802 mol O2 * 32.00 g/mol = 25.7 g O2

I personally love this particular chemical reaction. A catalyst for this decomposition is sugar and I use a gummy bear to demonstrate this reaction. Feel free to reach out if you would like to work one-on-one in a tutoring session.

Hope that helps!

Best,

Tenaya