question_answer

\[{{C}_{4}}{{H}_{6}}{{O}_{4}}A\xrightarrow{\Delta }{{C}_{3}}{{H}_{6}}{{O}_{2}}B\xrightarrow[\Delta ]{sodalime}C\] Compound C is a hydrocarbon, occupying approx 0.75 L volume per gram. Identify A and B.

A)  Tartaric acid, propanoic acid

B)  Succinic acid, succinic anhydride

C)  Maleic anhydride, maleic acid

D)  Methyl malonic acid, propanoic acid

Correct Answer: D

Solution :

\[\underset{A}{\mathop{{{C}_{4}}{{H}_{6}}{{O}_{4}}}}\,\xrightarrow{\Delta }\underset{B}{\mathop{{{C}_{3}}{{H}_{6}}{{O}_{2}}}}\,\] From above equation, it is clear that \[C{{O}_{2}}\] is lost due to heating. Thus, A is a dibasic acid with two -COOH groups on same carbon atom (gem position). Thus, A is                 \[\xrightarrow[\Delta ]{Soda\text{ }lime}\underset{\begin{smallmatrix}  C \\  ethane \end{smallmatrix}}{\mathop{C{{H}_{3}}C{{H}_{3}}}}\,\] For 1 mole of C again, \[C{{H}_{3}}C{{H}_{3}}(mov\,\,wt=30)\] \[\therefore \] 30 g of C occupies volume = 22.42 \[\therefore \] 1 g of C with occupy volume \[=\frac{22.4}{30}\] \[\simeq 0.75\text{ }L\]