What is the proper name for Fe(NO3)3? (a) iron (II) nitrate (b) iron (III) nitrate (c) iron (II) nitrite (d) iron (III) nitrite What is the proper name for Fe(NO3)3? (a) iron (II) nitrate (b) iron (III) nitrate (c) iron (II) nitrite (d) iron (III) nitrite
The correct answer and explanation is:
The proper name for Fe(NO₃)₃ is iron (III) nitrate. The correct answer is (b) iron (III) nitrate.
Explanation:
- Identifying the Metal and Its Oxidation State:
- The symbol “Fe” represents iron, a transition metal. Transition metals can have multiple oxidation states, so it is necessary to determine which one applies here.
- The nitrate ion, NO₃⁻, has a charge of -1. Since there are three nitrate ions in the formula, the total negative charge is 3×(−1)=−33 \times (-1) = -3.
- To balance the overall charge to neutral, the iron atom must have a charge of +3. This is why the iron in this compound is in the +3+3 oxidation state.
- Naming Transition Metal Compounds:
- When naming compounds with transition metals, Roman numerals are used to indicate the oxidation state of the metal.
- For Fe(NO₃)₃, the iron ion has a +3+3 charge, so the correct name is iron (III).
- Identifying the Polyatomic Ion:
- The NO₃⁻ ion is called nitrate, not nitrite. Nitrite is a different polyatomic ion with the formula NO₂⁻.
- In Fe(NO₃)₃, the nitrate ions are the anionic component of the compound.
- Combining the Name:
- The name of the cation (iron) is written first, followed by its oxidation state in Roman numerals in parentheses. Then, the name of the anion (nitrate) is written.
- Thus, the proper name is iron (III) nitrate.
Common Mistakes:
- Choosing iron (II) nitrate: This would imply Fe²⁺, which is incorrect because the compound Fe(NO₃)₃ requires Fe³⁺ to balance the three nitrate ions.
- Confusing nitrate (NO₃⁻) with nitrite (NO₂⁻): Always check the number of oxygen atoms to differentiate between the two.
In conclusion, Fe(NO₃)₃ is correctly named iron (III) nitrate because the iron ion has a +3 charge and the anion is nitrate.