BHU PMT BHU PMT Solved Paper-2001

  • question_answer
    The test used for the distinction of\[HCOOH\]and\[C{{H}_{3}}COOH\]is treatment with:

    A)  sodium                               

    B)  sodium hydroxide

    C)  Tollen's reagent              

    D)  alcohol

    Correct Answer: C

    Solution :

                     Key Idea: During distinction test both reactants should produce two different smells or colour or only one should react:  With sodium: Both of them react with sodium to form salt and hydrogen \[2HCOOH+2Na\xrightarrow{{}}2HCOONa+{{H}_{2}}\] \[2C{{H}_{3}}COOH+2Na\xrightarrow[{}]{{}}2C{{H}_{3}}COONa+{{H}_{2}}\] So, it cannot be used as distinguishing test.  With\[\mathbf{NaOH}\] \[HCOO{{H}_{4}}+NaOH\xrightarrow[{}]{{}}HCOONa+{{H}_{2}}O\] \[C{{H}_{3}}COOH+NaOH\xrightarrow{{}}C{{H}_{3}}COONa\]                                                                     \[+{{H}_{2}}O\] \[\because \]both of them give same type of compounds. \[\therefore \]It cannot be used as distinguishing test.  With alcohol: All acids react with alcohol to produce sweet smelling ester. \[\therefore \]It cannot be used as distinguishing test  With Tollen's reagent: \[HCOOH\xrightarrow[{}]{Tollen's\text{ }reagent}silver\text{ }mirror\] (\[\because \] HCOOH reduces Tollen's reagent) \[C{{H}_{3}}COOH\xrightarrow[{}]{\text{ }Tollen's\,reagent}no\text{ }reaction.\] So, Tollen's   reagent is   used to distinguishing them


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