The Question is from neet-chemistry solutions colligative-properties, and it was created by the author A.RAMA NAGESWARARAO

Question

Two solutions, A and B, are prepared by dissolving a non-volatile solute in different solvents. Solution A has a higher boiling point elevation than solution B, even though both solutions have the same molality. Which of the following statements is the MOST likely explanation for this observation?

A.RAMA NAGESWARARAO · Accepted Answer

## CORE INFORMATION
✓ **Answer**: A
## CONCEPT FRAMEWORK
 **Primary Concept**: Boiling point elevation and colligative properties
 **Related Topics**: Ebullioscopic constant, molality, colligative properties
 **Prerequisites**: Understanding of colligative properties and their dependence on the number of solute particles.
## SOLUTION PATHWAY
**Given Information**:
  * Two solutions (A and B) with the same molality.
  * Solution A has a higher boiling point elevation than solution B.
  * Non-volatile solute in both solutions.
**Method & Steps**:
 1. Understand Boiling Point Elevation:
  Reasoning: The boiling point elevation ($\Delta T_b$) is a colligative property, meaning it depends on the concentration of solute particles, not their identity.  It's directly proportional to the molality ($m$) of the solution and the ebullioscopic constant ($K_b$) of the solvent.
  Formula/Rule:  $\Delta T_b = K_b 	imes m 	imes i$, where $i$ is the van't Hoff factor (accounts for dissociation or association of solute).
 2. Analyze the given information:
  Working: Since both solutions have the same molality ($m$), the difference in $\Delta T_b$ must be due to either a difference in $K_b$ or $i$.  Assuming no dissociation or association ($i=1$), the only remaining factor is the ebullioscopic constant.
  Key Point: The ebullioscopic constant is a property of the solvent, not the solute.
 3. Conclusion:
  Result:  Solution A has a higher boiling point elevation because its solvent has a higher ebullioscopic constant ($K_b$).
  Verification: If $K_{b,A} > K_{b,B}$ and $m_A = m_B$, then $\Delta T_{b,A} > \Delta T_{b,B}$ which matches the observation.
 ## OPTION ANALYSIS
A] ✓: Solution A's solvent has a higher ebullioscopic constant. This is the correct explanation as it directly relates to the formula for boiling point elevation. 
B] :x: Solution A's solvent has a lower ebullioscopic constant. This would lead to a lower boiling point elevation for solution A, contradicting the given information.
C] :x: The solute in solution A dissociates more than the solute in solution B. While dissociation increases the effective molality, this is not the most likely explanation since the problem states both solutions have the *same* molality.  This would imply that the molality given is already the effective molality.
D] :x: The solute in solution B dissociates more than the solute in solution A.  This would result in a higher boiling point elevation for solution B, contradicting the given information. 
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Confusing ebullioscopic and cryoscopic constants: Remember $K_b$ is for boiling point and $K_f$ is for freezing point.
  2.Ignoring the van't Hoff factor:  Remember to consider the dissociation or association of the solute if given information suggests it.
 **Quick Tips**:
  1.Remember the formula: $\Delta T_b = K_b 	imes m 	imes i$ is crucial for solving these types of problems.
  2.Focus on the solvent's properties when comparing boiling point elevations of solutions with the same molality.

A.RAMA NAGESWARARAO · Answer

The correct Option is "Solution A's solvent has a higher ebullioscopic constant."

A.RAMA NAGESWARARAO · Answer

Solution A's solvent has a lower ebullioscopic constant.

A.RAMA NAGESWARARAO · Answer

The solute in solution A dissociates more than the solute in solution B.

A.RAMA NAGESWARARAO · Answer

The solute in solution B dissociates more than the solute in solution A.

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