What is the correct name for the compound CoCl_2?

• A. Cobalt chloride
• B. Cobalt(II) chloride
• C. Cobalt(III) chloride
• D. Cobalt dichloride

Answer: (B)

Verified step by step guidance

1. Identify the metal and its possible oxidation states. Cobalt (Co) can have multiple oxidation states, commonly +2 and +3.
2. Determine the charge on the chloride ion. Chloride (Cl) has a charge of -1.
3. Since the formula is CoCl_2, there are two chloride ions, each with a -1 charge, giving a total negative charge of -2.
4. To balance the charges, cobalt must have a +2 charge, so the oxidation state of cobalt in CoCl_2 is +2.
5. Name the compound by stating the metal with its oxidation state in Roman numerals followed by the name of the anion. Thus, the correct name is Cobalt(II) chloride.