Quiz of the Week

Quiz of the Week - Chemistry 221 Oxidation Numbers

Master the concepts from this week's material by trying these quiz questions which will NOT affect your grade in any way. All scoring is anonymous and known only to you, the user! If you have any questions, please contact me. Good luck!

A Quick Review of Oxidation Numbers

Atoms in their Natural State
- Atoms in their natural state will always have an oxidation number of zero.
- Examples include Cl_2(g), H_2(g), Na_(s), Hg_(l), N_2(g), Fe_(s), etc.
Fluorine
- Fluorine is always -1 in compounds with other elements.
Oxygen
- Oxygen is always -2 in compounds with other elements except when combined with fluorine or peroxides.
Chlorine, Bromine and Iodine
- Cl, Br and I will always be -1 in compounds with other elements unless combined with oxygen or fluorine.
Hydrogen
- Hydrogen is always +1 in compounds with other elements except when combined with metals to form metal hydrides. The oxidation number for a hydride (H^-) is -1.
Ions of a single atom
- For ions with only a single atom, the oxidation number is equal to the charge on the ion.
- For example, the sodium ion, Na⁺, has an oxidation number of +1.

Chemistry 221 - Oxidation Numbers

1. What is the oxidation number of P in H₃PO₄?
2. What is the oxidation number of N in NH₄MnO₄?
3. What is the oxidation number of Mn in NH₄MnO₄?
4. What is the oxidation number of C in C₂H₄O₂?
5. What is the oxidation number of Xe in XeO₄^2-?
6. What is the oxidation number of S in H₂S?
7. What is the oxidation number of Fe in FeCl₅?
8. Does the carbon in CO₂ have a higher oxidation number than the carbon in C₂H₄?
9. Does the sulfur in H₂S have a higher oxidation number than the sulfur in S₈?
10. Does the sulfur in H₂S have a higher oxidation number than the sulfur in H₂SO₄?
11. What is the oxidation number of H in CaH₂?
12. What is the oxidation number of O in OF₂^-1?
13. What is the oxidation number of Cl in OCl^-1?
14. Does the nitrogen in HNO₃ have a higher oxidation number than the nitrogen in NO₂?
15. What is the oxidation number of As in H₂AsO₄^-1?