Sort the following chromium compounds by whether the cation is chromium(II) or chromium(III). Cr2S3, Cr3P2, Crl3, CrO, CrBr2, CrN.

How would I solve this? Soo stuck. Thanks!
-MC

1 answer

One at a time. See Cr2S3.
How did it get that formula? I use the "cross charge" method which means Cr must be 3 and S must be 2.i ignore the charge of + and -; I figure the cation will be + and the anion will be -.

CrI3. Cr must be 3 and I must be 1.

This method won't work on 1:1 compounds like CrO. You know, however, that O is -2 so Cr must be +2.