Advantages
of corrosion​

Protection : Surface corrosion forms an oxide layer which further protects the inner metal form corrosion

.

Corrosion prevents corrosion : Some metals like zinc are used as sacrificial anodes to prevent corrosion to other metal.

Galvanic corrosion : The principle on which primary batteries work.

Following are the advantages of corrosion: A layer of protection: A layer of oxide is formed in surface corrosion, which protects the inner metal from corrosion. Sacrificial anodes such as zinc is used as a preventive measure to stop corrosion of other metals.

Explanation:

first, consult an activity series chart to determine if al is more reactive than fe. it is, so it will replace the fe. now, one can continue with the problem.

next, make sure you have a correctly balanced equation.

3feo + 2al ==> 3fe + al2o3

now, determine which reactant (feo or al) is in limiting supply.

moles feo present = 125 g x 1 mole/71.8 g = 1.74 moles

moles al present = 25.0 g x 1 mole/26.98 g = 0.927 moles

since from the balanced equation, it take 3 mol feo for every 2 mol al, al will be limiting.

you can determine this simply by dividing moles of each by their coefficient in the balanced equation. for example: 1.74/3 = 0.58 and 0.927/2 = 0.464. al is less, so it is limiting.

finally, using the stoichiometry in the balanced eq. determine mass of fe that can be produced from 0.927 moles of al.

0.927 moles al x 3 moles fe/2 moles al x 55.8 g/mole = 77.6 g