Question

Consider the reaction below.

2Al2O3 --> 4Al + 3O2

How many moles of oxygen are produced when 26.5 mol of aluminum oxide are decomposed?
(a) 17.7 mol
(b) 19.9 mol
(c) 39.8 mol
(d) 53.0 mol

Answer 1

(b) 19.9 moles

Step-by-step explanation:

To convert from moles Al to moles O₂, you need to multiply the given value by the mole-to-mole ratio of each component. This ratio is constructed via the coefficients in the balanced reaction. The desired unit (moles O₂) should be placed in the numerator to allow for the cancellation of units.

2 Al₂O₃ ----> 4 Al + 3 O₂
^ ^

26.5 moles Al 3 moles O₂
--------------------- x ---------------------- = 19.9 moles O₂
4 moles Al