Which of the following can be referred to as a d7 ion? * O Cu4+ o Mn 4+ O O O Ni4+ O None of the above .

Transition metals are known to have incompletely filled d- orbitals. For this reason, they are commonly referred to as the d- block. Cu4+  is a d7 ion.

An ion is formed when electrons are lost from or gained in a neutral atom.

An ion is a positively or negatively charged chemical specie. Chemical species form ions by loss or gain of electrons.

An atom is neutral if it has equal number of protons and electrons. When an atom has lost electrons, it forms a positive ion.

Copper has electronic configuration; 1s2 2s2 2p6 3s2 3p6 4s2 3d9. When four electrons are lost, its electronic configuration now becomes;

1s2 2s2 2p6 3s2 3p6 3d7.

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

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