Write down the IUPAC name of K 3 Cr C 2 O 4 3 .

K 3 Cr C 2 O 4 3 is made up of the cation K + and the anion Cr C 2 O 4 3 3 - C 2 O 4 is a negatively charged ligand with - 2 charge on it. Let the oxidation state of Cr be x . ⇒ 3 ( + 1 ) + x + 3 ( - 2 ) = 0 ⇒ 3 + x - 6 = 0 ⇒ x - 3 = 0 ⇒ x = 3 So, the oxidation state of Cr is 3 . Following things are to be kept in mind while writing the IUPAC name of an anionic complex: 1) While writing the IUPAC name of the complex, the cationic part of the complex is written first and then the anionic part. 2) Ligands are written in alphabetical order, mentioning their respective numbers first prefixed as tri, di, etc., followed by their names. Here, we have a total 3 ions of ligand C 2 O 4 2 - , named as trioxalato. 3) Here, since the complex ion is negatively charged, the central metal ion's name should end with the suffix 'ate', and its oxidation number should be written in Roman numeral in closed brackets. 4) It must be noted that the names of all species should start with small letters and must not start with capital letters. So, the IUPAC name of K 3 Cr C 2 O 4 3 will be potassium trioxalatochromate(III).