Redox Reactions Review

Is calcium oxidized or reduced in the following reaction? 2CaO--> 2Ca + O₂

• Oxidized

• Reduced

• Neither Oxidized nor Reduced

Answer explanation

Calcium is reduced in the reaction because it gains electrons to form Ca from CaO, which indicates a reduction reaction.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

In the reaction Zn + H₂O --> ZnO₂ + H₂ which element, if any, is oxidized?

• Zinc

• Hydrogen

• Oxygen

• None

Answer explanation

Zinc is oxidized in the reaction because it loses electrons, going from Zn to ZnO₂, which indicates an increase in oxidation state.

Another name for a "oxidation-reduction" reaction is

• chemical reaction

• neutralization reaction

• redox reaction

• nuclear reaction

Answer explanation

The term 'redox reaction' is another name for an oxidation-reduction reaction

What substance is oxidized in the following reaction?4Fe + 3O₂ --> 2Fe₂O₃

• Iron

• Fluorine

• Oxygen

Answer explanation

In the given reaction, iron (Fe) is oxidized as it gains oxygen atoms from O₂ to form iron oxide (Fe₂O₃).

If in a reaction, copper is reduced; its number of electrons has:

• Varies randonly

• Remains constant

• Decreased

• Increased

Answer explanation

When copper is reduced, it gains electrons, so the number of electrons increases.

Tags

NGSS.HS-PS1-2

If an atom loses electrons during a chemical reaction, the atom was:

• Oxidized

• Reduced

• Neutralized

• Precipitated

Answer explanation

If an atom loses electrons during a chemical reaction, it is oxidized. Oxidation involves the loss of electrons.

Tags

NGSS.HS-PS1-2

What element is being Oxidized?

• N

• H

• O

• S

Answer explanation

Sulfur (S) is being oxidized. It is the correct answer choice for the element undergoing oxidation in the given question.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

What element is being Reduced?

• N

• H

• O

• S

Answer explanation

The element being Reduced is N (Nitrogen). Reduction involves gaining electrons, and in this case, Nitrogen is gaining electrons to form a reduced compound.

Tags

NGSS.HS-PS1-2

What element is being Oxidized?

• I

• H

• S

• O

Answer explanation

The element being oxidized is S (sulfur). In a redox reaction, oxidation involves the loss of electrons, and in this case, sulfur is losing electrons, indicating it is being oxidized.

Tags

NGSS.HS-PS1-2

What is the oxidation number of N in NO₂-1?

• -3

• +4

• -2

• +3

Answer explanation

The oxidation number of N in NO2-1 is +3 because oxygen has an oxidation number of -2, and the overall charge of the ion is -1, so N must have an oxidation number of +3 to balance the charges.