what does (VI) in chromium (VI) sulfide mean
The correct answer and explanation is:
Correct Answer:
The (VI) in chromium (VI) sulfide indicates the oxidation state (or oxidation number) of chromium, which in this case is +6.
Explanation (300 words):
In chemistry, especially in the naming of ionic compounds involving transition metals, Roman numerals are used to indicate the oxidation state of the metal. Transition metals can have more than one possible oxidation state, so it’s important to specify which one is being used in a compound.
In chromium (VI) sulfide, the element chromium (Cr) is a transition metal that can exhibit several oxidation states, commonly +2, +3, and +6. The Roman numeral (VI) tells us that in this compound, chromium is in the +6 oxidation state.
Let’s break this down with the other element in the compound: sulfide, which refers to the sulfide ion (S²⁻). Each sulfide ion has a charge of -2.
To form a neutral compound, the total positive and negative charges must balance. If chromium is in the +6 oxidation state (Cr⁶⁺), and sulfide is -2 (S²⁻), you can determine the formula by balancing charges:
- One Cr⁶⁺ ion contributes +6
- Each S²⁻ contributes -2
- To balance +6, you need three S²⁻ ions:
→ 3 × (-2) = -6
So, the formula of chromium (VI) sulfide is CrS₃.
This method of using Roman numerals in names is called the Stock system of nomenclature and is essential for clarity when dealing with transition metals, which can form multiple ions with different charges.
For example:
- Chromium(III) chloride = CrCl₃ (Cr³⁺)
- Chromium(VI) oxide = CrO₃ (Cr⁶⁺)
- Chromium(II) sulfide = CrS (Cr²⁺)
Conclusion: The (VI) in chromium (VI) sulfide means that chromium has a +6 oxidation state in the compound, which is crucial for determining its correct chemical formula and structure.