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Question #44461
The Question
A sample of propane () undergoes photochemical monochlorination at . The relative reactivity of and C-H bonds towards chlorine radicals is . The major monochlorinated product (A) is isolated based strictly on its theoretical kinetic yield. Compound (A) is then treated with in dry ether, followed by bubbling and subsequent acidic workup () to yield compound (B). The entire quantity of (B) produced is dissolved in of a non-polar solvent (dielectric constant ) having a cryoscopic constant . Assuming (B) undergoes complete dimerization in this solvent due to intermolecular hydrogen bonding, what is the freezing point depression () of the resulting solution?
Options
- A.
0.20 K
- B.
0.35 K
- C.
0.40 K
- D.
0.70 K
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Numerical_Precision
Improve calculation stamina and avoid rounding errors in high-stakes competitive examinations.
Concepts Behind This Question
Free Radical Substitution Selectivity|Spontaneity Criteria|Van’t Hoff Factor (i) Application
Why This Question Is Tricky
Common Mistakes
This problem tests a student's ability to bridge organic kinetic control with physical chemistry non-ideality.
The first trap lies in the regioselectivity of free radical halogenation; students often assume either a 100% yield of the most stable radical product or a purely statistical distribution, ignoring the specific relative reactivity of C-H bonds.
The second trap is the Van't Hoff factor (i); students who blindly apply the colligative property formula will fail to account for the dimerization of carboxylic acids in low dielectric constant solvents, missing the i = 0.5 correction.
Quick Facts About This Question
Question Information
| Subject | Chemistry |
| Chapter | Hydrocarbons - Class 11 Part 2 |
| Concept | Free Radical Substitution Selectivity |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |