Question

1. acetonitrile (ch3cn) is an important industrial chemical. among other things, it is used to make plastic moldings, which have multiple uses, from car parts to lego bricks. which statement about acetonitrile is true? (hint: draw the structure for ch₃cn)

a. acetonitrile has all single bonds.
b. acetonitrile has no lone pairs of electrons.
c. acetonitrile has one triple bond.
d. acetonitrile has 22 valence electrons in its lewis structure.
e. one of the carbon atoms has a formal charge of -1 and the nitrogen atom has a formal charge of +1.

Explanation:

Step1: Draw Lewis structure

Carbon has 4 valence - electrons, hydrogen has 1, and nitrogen has 5. In $CH_3CN$, the left - hand carbon is bonded to three hydrogens and one carbon by single bonds, and the right - hand carbon is triple - bonded to nitrogen.

Step2: Analyze bond types

The structure of $CH_3CN$ has three $C - H$ single bonds, one $C - C$ single bond, and one $C\equiv N$ triple bond. So, it does not have all single bonds (a is false).

Step3: Analyze lone pairs

The nitrogen atom in $C\equiv N$ has one lone pair of electrons (b is false).

Step4: Confirm triple bond

As drawn, $CH_3CN$ has one $C\equiv N$ triple bond (c is true).

Step5: Calculate valence electrons

The number of valence electrons in $CH_3CN$: $(4\times2)+(1\times3)+5 = 16$ (d is false).

Step6: Calculate formal charges

For the left - hand carbon: $FC = 4-(4 + 0)=0$. For the right - hand carbon: $FC = 4-(2 + 3)= - 1$. For nitrogen: $FC = 5-(2 + 3)=0$ (e is false).

Answer:

C. Acetonitrile has one triple bond.