In this post, we will determine the oxidation numbers in chlorine dioxide – ClO₂.

To determine the oxidation number of an atom(s) in a molecule or an ion, start with the known oxidation numbers and the rules summarized below:

 

 

Keep in mind that the summary is zero for neutral molecules and is equal to the charge for ions.

For ClO₂ the element with a standard oxidation state is oxygen which is -2, and we need to determine the oxidation state of the chlorine. 

Rule 8 – The oxidation of oxygen is –2:

Assign x for the oxidation state of C and set up an equation:

x + 2(-2) = 0,  x = +4

 

 

Further Reading

• Solutions
• Strong and Weak Electrolytes
• Dissociation of Ionic Compounds
• Molecular, Ionic, and Net Ionic Equations
• Molarity 
• Dilution
• Ion Concentration
• Precipitation Reactions
• Definitions of Acids and Bases
• Naming Acids and Bases
• Acid-Base Reactions
• Displacement Reactions
• Predicting The Products of Chemical Reactions
• Stoichiometry of Reactions in Aqueous Solutions
• Acid-Base Titrations
• Oxidation State
• Oxidation-Reduction (Redox) Reactions
• Balancing Redox Reactions
  Reactions in Aqueous Solutions – Practice Problems

 

More examples of the oxidation state in this multiple-choice quiz: