The value of ebullioscopic constant depend upon

Options

A. `Delta H_("solution")`
B. Nature of solvent
C. Nature of solute
D. Freezing point of solution

Answer

To determine the factors on which the value of the ebullioscopic constant (Kb) depends, we can analyze the formula and the variables involved. Here’s a step-by-step breakdown:

### Step 1: Understand the ebullioscopic constant
The ebullioscopic constant (Kb) is a property of the solvent that indicates how much the boiling point of a solution will increase compared to the pure solvent. It is used in the formula for calculating the elevation of boiling point (ΔTb).

### Step 2: Review the formula for ΔTb
The elevation of boiling point is given by the equation:
\[ \Delta T_b = K_b \cdot m \]
where \(m\) is the molality of the solution.

### Step 3: Analyze the formula for Kb
The ebullioscopic constant can be calculated using the formula:
\[ K_b = \frac{m_a \cdot R \cdot T_b^2}{\Delta H_{vap} \cdot 1000} \]
where:
- \(m_a\) = molar mass of the solvent
- \(R\) = universal gas constant
- \(T_b\) = boiling point of the pure solvent
- \(\Delta H_{vap}\) = enthalpy of vaporization of the solvent

### Step 4: Identify the dependencies
From the formula, we can see that:
- Kb depends on the molar mass of the solvent (\(m_a\)).
- Kb depends on the boiling point of the solvent (\(T_b\)).
- Kb depends on the enthalpy of vaporization (\(\Delta H_{vap}\)).
- Kb does not depend on the solute or any properties related to the solute.

### Step 5: Conclusion
The value of the ebullioscopic constant (Kb) depends on:
1. The molar mass of the solvent.
2. The boiling point of the solvent.
3. The enthalpy of vaporization of the solvent.

Thus, the answer to the question is that the ebullioscopic constant depends on the nature of the solvent.