Which formula/name pair is incorrect?
a. Fe3SO3 iron (III)sulfide
b. FeSO3 iron (ll)sulfide
c. Fe Siron (ll)sulfide
d. FeSO4 iron (II)sulfate
e. Fez53 iron (Ill)sulfide
The Correct Answer and Explanation is :
The incorrect formula/name pair is c. Fe Siron (II) sulfide.
Explanation:
In this case, the error lies in the way the chemical formula and name are presented. Let’s break down the rest of the pairs and identify the issue:
a. Fe₃SO₃ iron (III) sulfide:
- The formula Fe₃SO₃ suggests that there are three iron (Fe) atoms for every three sulfite (SO₃) ions. The name “iron (III) sulfide” indicates that the iron has a +3 oxidation state. This is consistent with the formula because iron in the +3 oxidation state typically forms compounds like iron (III) sulfide (Fe₂(SO₃)₃). However, the correct empirical formula for iron (III) sulfide should be Fe₂(SO₃)₃ instead of Fe₃SO₃. This suggests a small error in the formula, but the naming is correct for iron (III) sulfide.
b. FeSO₃ iron (II) sulfide:
- The formula FeSO₃ represents iron (II) sulfite, where iron has a +2 oxidation state, which is correct. The name “iron (II) sulfide” matches this oxidation state, so this pair is correct.
c. Fe Siron (II) sulfide:
- The formula Fe Siron is nonsensical. “Siron” is not a valid chemical term or ion. It seems to be a typo or error in the name. The correct formula should be FeSO₃ for iron (II) sulfide. The name “iron (II) sulfide” would be accurate when referring to iron in the +2 oxidation state. This makes option c incorrect.
d. FeSO₄ iron (II) sulfate:
- The formula FeSO₄ represents iron (II) sulfate, which is a common compound where iron is in the +2 oxidation state. The name “iron (II) sulfate” is accurate for this compound. Therefore, this pair is correct.
e. Fe₂S₃ iron (III) sulfide:
- The formula Fe₂S₃ represents iron (III) sulfide, which has iron in the +3 oxidation state, as indicated by the name “iron (III) sulfide.” Therefore, this pair is correct.
Conclusion:
Option c. Fe Siron (II) sulfide is incorrect because “Siron” is not a valid term in chemistry and appears to be a typographical error. The correct formula and name would be FeSO₃ iron (II) sulfide.