. For each of the following oxidation-reduction reactions of

metals with nonmetals, identify which element is oxidized and

which is reduced.

a. 4Na ( s ) + O 2 ( g ) → 2Na 2 O ( s )    b. Fe ( s ) + H 2 SO 4 ( aq ) → FeSO 4 ( aq ) + H 2 ( g )    c. 2Al 2 O 3 ( s ) → 4Al ( s ) + 3O 2 ( g )    d. 3Mg ( s ) + N 2 ( g ) → Mg 3 N 2 ( s )

(a)

Interpretation:

In the given oxidation-reduction reaction, the species that oxidized and that reduced should be identified.

Concept Introduction:

The oxidation-reduction reaction is also known as a redox reaction. In this reaction, one reactant is oxidized and other is reduced. The balancing of oxidation-reduction reaction can be done by simple method by comparing the number of each atoms on both sides of the reaction arrow without addition of hydrogen ion, water molecule and electrons from outside.

In the given oxidation reduction reaction, the oxidation state of sodium Na on left side of the reaction arrow is zero as it is present in its elemental state and that on right side is + 1 (most common oxidation state of sodium). Since, the oxidation state increases from zero to + 1 thus, sodium gets oxidized in the above reaction.

The oxidation state of oxygen in O2 is zero. Calculate the oxidation state of oxygen in Na2O

(b)

Interpretation:

In the given oxidation-reduction reaction, the species that oxidized and that reduced should be identified.

Concept Introduction:

The oxidation-reduction reaction is also known as a redox reaction. In this reaction, one reactant is oxidized and other is reduced. The balancing of oxidation-reduction reaction can be done by simple method by comparing the number of each atoms on both sides of the reaction arrow without addition of hydrogen ion, water molecule and electrons from outside.

(c)

Interpretation:

In the given oxidation-reduction reaction, the species that oxidized and that reduced should be identified.

Concept Introduction:

The oxidation-reduction reaction is also known as a redox reaction. In this reaction, one reactant is oxidized and other is reduced. The balancing of oxidation-reduction reaction can be done by simple method by comparing the number of each atoms on both sides of the reaction arrow without addition of hydrogen ion, water molecule and electrons from outside.

(d)

Interpretation:

In the given oxidation-reduction reaction, the species that oxidized and that reduced should be identified.

Concept Introduction:

The oxidation-reduction reaction is also known as a redox reaction. In this reaction, one reactant is oxidized and other is reduced. The balancing of oxidation-reduction reaction can be done by simple method by comparing the number of each atoms on both sides of the reaction arrow without addition of hydrogen ion, water molecule and electrons from outside.