Chemical Reaction Patterns: Tutorial
? Question
With all the coefficients set to 1, how can you tell that the equation is not balanced?
Select all the correct answers.
The number of hydrogen atoms in the reactants does not equal the number in the produ
The number of nitrogen atoms in the reactants does not equal the number in the product
The number of ammonia molecules in the products does not equal the number in the rea
There are two molecules in the reactants, but there is only one molecule in the products.

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

fe 55.85 g/mol and h2o 18.02 g/mol.