What is the correct formula for iron(III) sulfide?
A. Fe₂S₂ B. Fe₂S C. FeS D. FeS₂ E. Fe₂S₃
The Correct Answer and Explanation is :
The correct formula for iron(III) sulfide is E. Fe₂S₃.
Explanation:
Iron(III) sulfide is a compound formed between iron and sulfur. In this context, the “III” in iron(III) indicates that iron has a +3 oxidation state. Understanding the oxidation states of the elements involved is crucial for determining the correct chemical formula.
- Oxidation States:
- Iron (Fe) can have multiple oxidation states, including +2 and +3. In iron(III) sulfide, iron is in the +3 oxidation state.
- Sulfur (S) typically has an oxidation state of -2 in sulfide compounds.
- Balancing Charges:
- To determine the correct formula, we need to balance the total positive and negative charges. Each iron atom contributes a +3 charge, while each sulfur atom contributes a -2 charge.
- To balance the charges in the compound, we can set up the following equation:
- If we let ( x ) be the number of iron atoms and ( y ) be the number of sulfur atoms, we need to solve for ( x ) and ( y ) in the equation:
[
3x + (-2y) = 0
]
- If we let ( x ) be the number of iron atoms and ( y ) be the number of sulfur atoms, we need to solve for ( x ) and ( y ) in the equation:
- To achieve charge neutrality, we find that for every 2 iron atoms (+6) we need 3 sulfur atoms (-6):
- Thus, ( 2(3) + 3(-2) = 0 ).
- Formula Construction:
- This gives us the formula ( \text{Fe}_2\text{S}_3 ). Here, we have two iron atoms and three sulfur atoms, which balances the charges perfectly.
- Chemical Properties:
- Iron(III) sulfide is a solid compound that can form through various reactions, including the direct combination of elemental iron and sulfur at elevated temperatures.
In summary, the correct chemical formula for iron(III) sulfide, based on oxidation states and charge balancing, is Fe₂S₃. This formula reflects the stoichiometric ratio of iron to sulfur in the compound, confirming that it comprises two iron atoms for every three sulfur atoms.