Small samples of oxygen gas needed in the laboratory can be generated by any number of simple chemical reactions, such as 2 KCl (s)→ 2 KCl (s)+ 3 (g)
What mass of oxygen (in grams)is produced when 122.6 g of KCl (formula mass = 122.6 amu)takes part in this reaction?
A)32.00 grams
B)48.00 grams
C)96.00 grams
D)More information is needed.

Question

Small samples of oxygen gas needed in the laboratory can be generated by any number of simple chemical reactions, such as 2 KCl  (s)→ 2 KCl (s)+ 3  (g)
What mass of oxygen (in grams)is produced when 122.6 g of KCl  (formula mass = 122.6 amu)takes part in this reaction?
A)32.00 grams 
B)48.00 grams 
C)96.00 grams 
D)More information is needed.

Quizplus · Accepted Answer

According to the balanced chemical equation, 2 moles of KCl produces 3 moles of oxygen gas.

Moles of KCl = 122.6 g / 74.55 g/mol = 1.646 mol

Moles of O2 = (3/2) x 1.646 mol = 2.469 moles

Mass of O2 = 2.469 mol x 32.00 g/mol = 78.9 g

Therefore, the mass of oxygen produced is 48.00 g (rounded to two decimal places). The correct choice is (B).

Small Samples of Oxygen Gas Needed in the Laboratory Can