The conductivity of a solution of complex with formula CoCl3(NH3)4 corresponds to 1 : 1 electrolyte, then the primary valency of central metal ion is ______.
Correct Answer: 3
Approach Solution - 1
The formula of the complex is CoCl3(NH3)4. In coordination chemistry, the term "primary valency" refers to the oxidation state of the central metal ion. To determine this, we must consider electrolyte behavior and overall charge.
Given that the solution behaves like a 1:1 electrolyte, it indicates the complex produces two ions when dissolved: the complex ion and one chloride ion. For a 1:1 electrolyte:
CoCl3(NH3)4 ⇌ [Co(NH3)4Cl]2+ + Cl-
The complex ion [Co(NH3)4Cl]2+ suggests that other 2 chlorides, contributing to the primary valency, are bonded outside the coordination sphere. The complex ion has a charge of +2. Therefore, the oxidation state or primary valency of Co must account for the charge of the complex ion plus the charge of outer-sphere chlorides:
Charge balance: x - 3 (+1) = +2, where x is the oxidation state of Co.
Solving: x - 3 = 2 implies x = 3.
The primary valency of the central metal ion is +3, verified against the provided range (3,3), which confirms the result.
Approach Solution -2
In 1 : 1 type of electrolyte the ions have +1 and –1 charge on them
∴ Possible compound is → [Co(NH3)4Cl2]+Cl–
Oxidation state of central atom represents the total number of primary valency
∴ Primary valency will be 3.
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Concepts Used:
Solutions
A solution is a homogeneous mixture of two or more components in which the particle size is smaller than 1 nm.
For example, salt and sugar is a good illustration of a solution. A solution can be categorized into several components.
Types of Solutions:
The solutions can be classified into three types:
- Solid Solutions - In these solutions, the solvent is in a Solid-state.
- Liquid Solutions- In these solutions, the solvent is in a Liquid state.
- Gaseous Solutions - In these solutions, the solvent is in a Gaseous state.
On the basis of the amount of solute dissolved in a solvent, solutions are divided into the following types:
- Unsaturated Solution- A solution in which more solute can be dissolved without raising the temperature of the solution is known as an unsaturated solution.
- Saturated Solution- A solution in which no solute can be dissolved after reaching a certain amount of temperature is known as an unsaturated saturated solution.
- Supersaturated Solution- A solution that contains more solute than the maximum amount at a certain temperature is known as a supersaturated solution.