Question

When heated, KClO3 decomposes into KCl and O2. 2 KClO3 -------------------> 2 KCl + 3O2 If this reaction produced 70.5 g of KCl, how much O2 was produced ( in grams)?

Answer 1

Molar mass of KCl = 1*MM(K) + 1*MM(Cl)

= 1*39.1 + 1*35.45

= 74.55 g/mol

mass of KCl = 70.5 g

mol of KCl = (mass)/(molar mass)

= 70.5/74.55

= 0.9457 mol

From balanced chemical reaction, we see that

when 2 mol of KCl forms, 3 mol of O2 is formed

mol of O2 formed = (3/2)* moles of KCl

= (3/2)*0.9457

= 1.4185 mol

Molar mass of O2 = 32 g/mol

mass of O2 = number of mol * molar mass

= 1.4185*32

= 45.4 g

Answer: 45.4 g