Question

What makes the cis Co(III) complex different from the trans Co(III) complex?@chemistry

Answer 1

Get two pairs of shoes, one red and one black. Put the shoes on each foot and each hand. There are two possibilities: (1) you could have both red shoes on your feet, both on your hands, one on your right foot and right hand, or one on your left food and left hand -- but in ALL cases both red shoes on the same side of your body (top, bottom, left or right) and the black shoes on the other side, or (2) you could have one red shoe on your left foot and one on your right hand, or one red shoe on your right foot and one on your left hand -- but in either case the two red shoes on opposite sides of your body.

If (1) then you are a "cis" complex: similar "ligands" (in this case the red shoes) are on the same side of you, the central atom. If (2) then you are a "trans" complex: similar ligands are on opposite sides of you, the central atom.