What is the chemical formula for the compound formed between chromium(III) ions and borate ions?

• A. Cr2(BO3)3
• B. Cr3(BO3)2
• C. Cr(BO3)2
• D. Cr(BO3)3

Answer: (A)

Verified step by step guidance

1. Identify the charge on the chromium(III) ion. The (III) indicates a +3 charge, so the ion is \(\mathrm{Cr^{3+}}\).
2. Determine the formula and charge of the borate ion. Borate is \(\mathrm{BO_3^{3-}}\), carrying a -3 charge.
3. Since both ions have charges of equal magnitude but opposite sign (+3 and -3), they combine in a 1:1 ratio to balance the charges.
4. Write the chemical formula by placing one chromium(III) ion and one borate ion together without needing additional subscripts: \(\mathrm{Cr(BO_3)}\).
5. Check the options given and note that the correct formula must reflect charge neutrality and proper ion ratios. If the borate ion is \(\mathrm{BO_3^{3-}}\) and chromium is \(\mathrm{Cr^{3+}}\), the formula is \(\mathrm{Cr(BO_3)}\); however, if the borate ion is different or the problem implies a different borate species, adjust accordingly.