What is the correct IUPAC name for the compound with the formula ${\mathrm{Co}}_2\left({\mathrm{SO}}_4\right)3$?

• A. Cobalt(II) sulfate
• B. Cobalt sulfate
• C. Dicobalt trisulfate
• D. Cobalt(III) sulfate

Answer: (D)

Verified step by step guidance

1. Identify the metal and its oxidation state in the compound. The formula is \(\mathrm{Co_2(SO_4)_3}\). Since sulfate ion \(\mathrm{SO_4^{2-}}\) has a charge of -2, calculate the total negative charge from the three sulfate ions: \$3 \times (-2) = -6$.
2. Determine the total positive charge needed to balance the compound. Since the compound is neutral, the two cobalt ions together must have a total charge of +6.
3. Calculate the oxidation state of each cobalt ion by dividing the total positive charge by the number of cobalt atoms: \(\frac{+6}{2} = +3\). So, each cobalt ion is in the +3 oxidation state.
4. Use the IUPAC naming convention for coordination compounds and ionic compounds: name the metal followed by its oxidation state in Roman numerals in parentheses, then the name of the anion. Here, the metal is cobalt and the oxidation state is III.
5. Combine the parts to form the correct IUPAC name: 'Cobalt(III) sulfate'. This indicates cobalt in the +3 oxidation state combined with sulfate ions.