Aluminum electroplating is a process by which aluminum is co

Aluminum electroplating is a process by which aluminum is coated onto a metal object. The object is submerged in a liquid solution containing Al2O3 molecules. An electric current breaks up these molecules into oxygen gas and aluminum atoms. The aluminum is attracted to the object to be coated and forms a thin aluminum film on its surface. If a car bumper needs to be plated with 245 g of aluminum using this electroplating process, what mass of oxygen gas is produced? Assume a mass of 27 atomic mass units (amu) for each aluminum atom and 16 amu for each oxygen atom. Answer in units of g.

Solution

Balance the equation for given process,

2 Al2O3 = 4 Al + 3 O2

moles of Al = 245 / 27 = 9.074 moles

moles of oxygen,

n = 3*9.074 / 4

n = 6.805

mass of oxygen,

m = 6.805*32

m = 217.22 g