Question

The number of nitrogen atoms in a semicarbazone molecule of acetone is ______.

Options

• 2

• 3

• 10

• 26

Answer 1

The number of nitrogen atoms in a semicarbazone molecule of acetone is 3.

Explanation:

The acetone interacts with semicarbazide creates semicarbazone as shown below.

\[\begin{array}{cc}
\ce{CH3}\phantom{...............................}\ce{CH3}\phantom{.........................}\\

\backslash\phantom{....................................}\backslash\phantom{........................}\\
\ce{C = O + H2N - NH - C - NH2 ->[- H2O] C = N - NH - C - NH2}\\
\phantom{....}/\phantom{......................}||\phantom{.............}/\phantom{................}||\phantom{...........}\\
\phantom{...}\ce{\underset{acetone}{CH3}}\phantom{...............}\ce{\underset{Semicarbazide}{O}}\phantom{........}\ce{CH3}\phantom{..........}\ce{\underset{Semicarbazone}{O}}\phantom{.......}
\end{array}\]

By removing the water molecule created by joining the acetone's O atom with the two hydrogen atoms from the terminal NH₂ group that is immediately connected to the NH in the semicarbazide, the acetone semicarbazone is created.

The molecular formula of acetone semicarbazone is C₄H₉N₃O and IUPAC name is propan-2-ylideneamino urea. Therefore, the number of nitrogen atoms in a semicarbazone molecule of acetone is 3.