In which group does each element have a total of four electrons in the outermost principal energy level

Group 14  

Explanation:

The elements of the Periodic Table are arranged into 18 Groups.

Among the "main group elements" — those in Groups 1, 2 and 13 to 18 — the number of valence electrons —  the number of electrons in the outermost energy level —  corresponds to the last digit of  the Group number.

Thus, Group 14 contains the elements with four valence electrons — C, Si, Ge, Sn, Pb, and Fl.

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