I need to know what is oxidized and what is reduced.

1. 2CoS(s) + 3O2(g) > 2CoO(s) + 2SO2(g)

2. 2Al(s) + 3F2(g) > 2AlF3(s)

3. ZnO(s) + H2(g) > Zn + H2O(g)

1. Reduction: O₂ ; Oxidation: S

2. Reduction: F ; Oxidation: Al

3. Reduction: Zn ; Oxidation: H

Explanation:

Determine the oxidation state of each element:

2 CoS → Cobalt acts with +2, S with -2

O₂ is at ground state. In ground state the elements has oxidation state of 0.

In CoO, the oxygen acts with -2

The oxidation state has decreased; oxygen was reduced.

In SO₂, sulfur acts with +4; oxidation state has increased, so S has been oxidized.

2. Both reactants are at ground state.

In AlF₃  Al has oxidation state of +3 and F, -1

Al increased the oxidation state → oxidation

F decreased the oxidation state → reduction

3. Hydrogen has 0 as oxidation state. In water, H has +1

It was increased → oxidation

Zn acts with +2, in the zinc oxide. As we have elemental Zn, the oxidation state is 0; it has decreased → reduction