Problem 73 - A Complete Resource Book in Chemistry for JEE Main

Question

Van't Hoff factor for a dilute solution of sodium argento cyanide is (a) 2 (b) \(0.25\) (c) \(3.0\) (d) \(0.50\)

Step-by-Step Solution

Answer

The Van't Hoff factor for sodium argento cyanide is 2, option (a).

Step 1: Understanding the Problem

The Van't Hoff factor is a measure of the effect of a solute on the colligative properties of a solution. For sodium argento cyanide ( Na[Ag(CN)_2] ), it is important to determine how it dissociates in solution.

Step 2: Dissociation of Sodium Argento Cyanide

Sodium argento cyanide, Na[Ag(CN)_2], dissociates in the solution as follows:\[Na[Ag(CN)_2] \rightarrow Na^+ + [Ag(CN)_2]^-\]This dissociation results in two particles for each formula unit of sodium argento cyanide that dissociates.

Step 3: Calculating the Van't Hoff Factor

The Van't Hoff factor (i) is defined by the number of particles produced per formula unit of solute that dissolves. In our case, since Na[Ag(CN)_2] produces two ions upon dissolution, the Van't Hoff factor (i) should be equal to 2.

Step 4: Checking Solution Options

Compare the calculated Van't Hoff factor with the given options: (a) 2, (b) 0.25, (c) 3.0, (d) 0.50. The correct option that matches our calculated Van't Hoff factor is option (a) 2.

Key Concepts

Colligative Properties

When a solute dissolves in a solvent, it can alter the physical properties of the resulting solution. These changes are known as colligative properties. What makes them unique is that they depend on the number of solute particles present in the solution rather than the identity of those particles. Common colligative properties include:

• Vapor pressure lowering
• Boiling point elevation
• Freezing point depression
• Osmotic pressure

Each of these properties plays a crucial role in various applications, from everyday life (like freezing point depression in car antifreeze) to specialized scientific processes. Understanding how solute particles affect these properties can help us predict and manipulate solution behavior in predictable ways.

Ionic Dissociation

Ionic dissociation describes how ionic compounds separate into individual ions when dissolved in a solvent. This process is key to understanding several fundamental behaviors in solution chemistry. Take, for example, sodium argento cyanide \(Na[Ag(CN)_2]\). In an aqueous solution, each unit of this compound effectively dissociates to form one sodium ion \(Na^+\) and one complex ion \([Ag(CN)_2]^-\).

This results in the presence of additional particles within the solution, reinforcing colligative properties. Knowing the count of dissociated ions informs us of the Van't Hoff factor, which in this case equals 2. This knowledge helps predict the behavior of solutions containing ionic compounds. Ionic dissociation is therefore fundamental to understanding how solutes impact the properties of their solutions.

Sodium Argento Cyanide

Sodium argento cyanide, with the chemical formula \(Na[Ag(CN)_2]\), is an interesting compound due to its unique composition and properties. It contains a sodium ion and a complex ion \([Ag(CN)_2]^-\) where silver (Ag) and cyanide (CN) ions bond to create a stable, complex structure.

This compound finds practical use in processes such as electroplating because of its ability to dissociate and provide silver ions. Understanding its behavior in solution, including how it dissociates into its constituent ions, is crucial for predicting its effect on the solution's colligative properties. Knowledge about sodium argento cyanide's behavior helps in designing solutions for specific industrial applications.

Solution Chemistry

Solution chemistry is a broad and fascinating field that studies how substances dissolve, interact, and behave in liquids. It provides insight into essential chemical processes. Within this domain, critical topics such as solubility, concentration, and phase behavior are explored. Each has significant importance for both theoretical and practical applications in science and industry.

A fundamental part of solution chemistry is understanding how solutes like sodium argento cyanide influence solutions based on their dissociation effects and corresponding impact on colligative properties. These insights allow chemists to customize solutions to achieve desired properties, whether they are looking to modify boiling or freezing points, or control osmotic pressures.