The treatment of alkyl chlorides with aq | Class 12 Chemistry Chapter Haloalkanes and Haloarenes, Haloalkanes and Haloarenes NCERT Solutions

Welcome to the NCERT Solutions for Class 12 Chemistry - Chapter Haloalkanes and Haloarenes. This page offers a step-by-step solution to the specific question from Exercise 2, Question 20: . With detailed answers and explanations for each chapter, students can strengthen their understanding and prepare confidently for exams. Ideal for CBSE and other board students, this resource will simplify your study experience.

Question 20:

The treatment of alkyl chlorides with aqueous KOH leads to the formation of alcohols but in the presence of alcoholic KOH, alkenes are major products. Explain.

Answer:

In an aqueous solution, KOH almost completely ionizes to give OH - ions. OH - ion is a strong nucleophile, which leads the alkyl chloride to undergo a substitution reaction to form alcohol.

On the other hand, an alcoholic solution of KOH contains alkoxide (RO - ) ion, which is a strong base. Thus, it can abstract a hydrogen from the β-carbon of the alkyl chloride and form an alkene by eliminating a molecule of HCl.

OH - ion is a much weaker base than RO - ion. Also, OH - ion is highly solvated in an aqueous solution and as a result, the basic character of OH - ion decreases. Therefore, it cannot abstract a hydrogen from the β-carbon.


Study Tips for Answering NCERT Questions:

NCERT questions are designed to test your understanding of the concepts and theories discussed in the chapter. Here are some tips to help you answer NCERT questions effectively:

  • Read the question carefully and focus on the core concept being asked.
  • Reference examples and data from the chapter when answering questions about Haloalkanes and Haloarenes.
  • Review previous year question papers to get an idea of how such questions may be framed in exams.
  • Practice answering questions within the time limit to improve your speed and accuracy.
  • Discuss your answers with your teachers or peers to get feedback and improve your understanding.

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Comments

  • Himani Shukla
  • Mar 10, 2019

Basic medium does not mean RO-. There can be many sources of OH-. Poor explanation..


  • Rajan lubana
  • Mar 09, 2019

After searching in diff sites finally find a perfect answer to the question


  • Paresh
  • Feb 15, 2019

Thanks for making me understand


  • Mother diary
  • Feb 02, 2018

Ghosh


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Welcome to the NCERT Solutions for Class 12 Chemistry - Chapter . This page offers a step-by-step solution to the specific question from Excercise 2 , Question 20: The treatment of alkyl chlorides with aqueous KOH leads to the formation of alcohols but in the pres....