What is the correct name for the ionic compound with the formula (NH_4)_2CrO_4?

• A. Ammonium dichromate
• B. Chromium(II) ammonate
• C. Ammonium carbonate
• D. Ammonium chromate

Answer: (D)

Verified step by step guidance

1. Identify the cation and anion in the compound (NH_4)_2CrO_4. The cation is ammonium, NH_4^+, and the anion is chromate, CrO_4^{2-}.
2. Recognize that the formula shows two ammonium ions balancing one chromate ion, which means the compound is composed of ammonium and chromate ions in a 2:1 ratio.
3. Recall the naming conventions for ionic compounds: the cation name is stated first (ammonium), followed by the anion name (chromate).
4. Note that the compound does not contain dichromate (Cr_2O_7^{2-}) or carbonate (CO_3^{2-}), so names like ammonium dichromate or ammonium carbonate are incorrect.
5. Combine the names of the ions to give the correct name: ammonium chromate.