The coordination compound [Co(NH3)4(CN)2]Cl:
a) contains seven ligands.
b) has a coordination number of 6.
c) contains Co in the +2 oxidation state.
d) would not form a precipitate with AgNO3.
a) contains seven ligands.
The compound [Co(NH3)4(CN)2]Cl contains four ammonia molecules (NH3) and two cyanide molecules (CN-) as ligands. The total number of ligands is therefore six. Additionally, the chloride ion (Cl-) also acts as a ligand, making the total number of ligands seven.
To determine the correct statements about the coordination compound [Co(NH3)4(CN)2]Cl, let's analyze each option one by one:
a) The coordination compound contains seven ligands.
To determine the number of ligands, we need to count the number of individual entities that bind directly to the central metal ion. In this case, there are two types of ligands: NH3 (ammonia) and CN- (cyanide). Therefore, the compound contains a total of six ligands (four NH3 and two CN-). So option a) is incorrect.
b) The compound has a coordination number of 6.
The coordination number refers to the number of bonds formed to the central metal ion. In this case, the coordination number is equal to the total number of ligands bound to the metal. As mentioned earlier, there are six ligands in total (four NH3 and two CN-), so the coordination number is indeed 6. Hence, option b) is correct.
c) The compound contains Co in the +2 oxidation state.
To determine the oxidation state of the central metal ion (Co in this case), we need to consider the charges and the overall charge of the compound. In this case, the compound is a chloride salt [Co(NH3)4(CN)2]Cl. Each NH3 ligand has a neutral charge, CN- has a -1 charge, and Cl has a -1 charge. Since the compound carries a positive charge (due to the Cl- counterion), the sum of the ligand charges must equal the charge on the central metal ion. In this compound, Co is in the +2 oxidation state to balance the overall charge. So option c) is correct.
d) The compound would not form a precipitate with AgNO3.
To determine if a precipitate would occur, we consider the solubility rules. When AgNO3 is added to a solution, it can form an insoluble AgCN precipitate. Since the [Co(NH3)4(CN)2]Cl compound contains CN-, the addition of AgNO3 would result in the formation of AgCN precipitate. Therefore, option d) is incorrect.
In summary, the correct statements are:
b) The compound has a coordination number of 6.
c) The compound contains Co in the +2 oxidation state.