Which of the following represents the correct order of acidic strength ? (i) HC ≡ CH H 2 C = CH 2 CH 3- CH 3 (ii) HC ≡ CH CH 3- CH 3 H 2 C = CH 2 (iii) CH 3 C ≡ CH HC ≡ CH CH 3- C ≡ C - CH 3 (iv) HC ≡ CH CH 3- C ≡ CH CH 3- C ≡ C - CH 3

Question

Which of the following represents the correct order of acidic strength ? (i) HC ≡ CH > H 2 C = CH 2> CH 3- CH 3 (ii) HC ≡ CH > CH 3- CH 3> H 2 C = CH 2 (iii) CH 3 C ≡ CH > HC ≡ CH > CH 3- C ≡ C - CH 3 (iv) HC ≡ CH > CH 3- C ≡ CH > CH 3- C ≡ C - CH 3 (A) (i) and (iii) (B) (ii) and (iv) (C) (i) and (iv) (D) (iii) and (iv)

Tardigrade Admin · Accepted Answer

Due to the maximum percentage of s character (50 %), the s p hybridised orbitals of carbon atoms in ethyne molecules have highest electronegativity, hence, these attract the shared electron pair of the C - H bond of ethyne to a greater extent than that of the s p2 hybridised orbitals of carbon in ethene and the s p3 hybridised orbital of carbon in ethane. Thus in ethyne, hydrogen atoms can be liberated as protons more easily as compared to ethene and ethane.

Q. Which of the following represents the correct order of acidic strength ? (i) HC≡CH>H2​C=CH2​>CH3​−CH3​ (ii) HC≡CH>CH3​−CH3​>H2​C=CH2​ (iii) CH3​C≡CH>HC≡CH>CH3​−C≡C−CH3​ (iv) HC≡CH>CH3​−C≡CH>CH3​−C≡C−CH3​

(i) and (iii)

(ii) and (iv)

(i) and (iv)

(iii) and (iv)