What is the formula for chromium (VI) chlorate?
a. Cr6ClO3
b. Cr(ClO3)6
c. Cr6ClO2
d. Cr(ClO2)6
The correct answer and explanation is:
The correct formula for chromium (VI) chlorate is Cr(ClO₃)₆.
Explanation:
Chromium (VI) refers to the oxidation state of chromium in which it has a +6 charge. To determine the correct formula, it’s essential to understand the nature of the ions involved.
- Chromium (VI): Chromium in its +6 oxidation state (Cr⁶⁺) will combine with other ions in a way that neutralizes the overall charge of the compound. In this case, the chromium ion will bond with chlorate ions (ClO₃⁻), which have a -1 charge.
- Chlorate ion: Chlorate (ClO₃⁻) is a polyatomic ion composed of chlorine and oxygen. It carries a -1 charge. When chromium (VI) combines with chlorate ions, the number of chlorate ions needed will depend on the charge of the chromium ion.
- Balancing the charges: Chromium (VI), having a +6 charge, will need six chlorate ions, each carrying a -1 charge, to balance the charge and create a neutral compound. Therefore, the correct ratio is one chromium ion for every six chlorate ions. This results in the formula Cr(ClO₃)₆.
In contrast, other options are incorrect because:
- Cr6ClO3 implies six chromium atoms, which is incorrect for chromium (VI), where there should only be one chromium ion.
- Cr6ClO2 and Cr(ClO2)6 would imply either incorrect oxidation states or incorrect stoichiometry of the chlorate ion (ClO₃⁻), as chlorate contains three oxygens and the formulas in these options suggest something else.
Hence, Cr(ClO₃)₆ is the correct formula for chromium (VI) chlorate, as it follows proper charge balancing and oxidation state conventions.