Question

Question: Label the polar bonds in each molecule. Indicate the direction of the net dipole (if there is one).

$$\begin{gathered} \mathbf{a}\mathbf{.}\mathbf{}{\mathbf{CHBr}}_{\mathbf{3}} \\ \mathbf{b}\mathbf{.}\mathbf{}{\mathbf{CH}}_{\mathbf{3}}{\mathbf{CH}}_{\mathbf{2}}{\mathbf{OCH}}_{\mathbf{2}}{\mathbf{CH}}_{\mathbf{3}} \end{gathered}$$

c.

d.

Short answer

Answer

a. Polar,

b. Polar,

c. Polar,

d. Nonpolar,

Step-by-step solution

 Step-by-Step Solution Step 1: Determination of polar bonds      

The polar bonds are determined by the large electronegativity difference between the two atoms, which form the corresponding bond.

For example, the bond between carbon and hydrogen (C-H) will be nonpolar because the electronegativity difference is very small.

The bond between carbon and oxygen (C-O) will be polar because of the large electronegativity difference.

Determination of polar molecules

The polar molecules are determined based on the net dipole moment magnitude.

• If the net dipole moment of a molecule is zero, then the molecule is nonpolar.
• If the net dipole moment of a molecule is nonzero, then the molecule is polar.

Explanation of the given polar and nonpolar molecules

a. ${\mathrm{CHBr}}_3\ne {\mathrm{sp}}^2$

In the given molecule, the electronegativity value of the given atoms follows the order given below:

$\mathrm{H}\simeq \mathrm{C}<\mathrm{Br}$

Since the carbon (central atom) has four bond pairs and zero lone pair of electrons, then according to VSEPR theory, the molecule has tetrahedral geometry.

Therefore, the net dipole is in the direction of bromine. Hence, the molecule is polar.

Representation of dipole moment of (a)

Polar, net dipole moment $\ne 0$

b. In the given molecule, the electronegativity value of the given atoms follows the order given below:

$\mathrm{H}\simeq \mathrm{C}<\mathrm{O}$

Since the oxygen (central atom) has two bond pairs and two lone pairs of electrons, then according to VSEPR theory, the molecule has a bent structure.

Therefore, the net dipole is in the direction of O, and the molecule is polar.

Representation of dipole moment of (b)

Polar, net dipole moment$\ne 0$

c. In the given molecule, the electronegativity value of the given atoms follows the order given below:

$\mathrm{H}\simeq \mathrm{C}<\mathrm{Br}$

Since the carbon (central atom) has ${\mathrm{sp}}^2$ hybridization, the molecule is a planar structure.

Therefore, the net dipole is in the direction of Br, and the molecule is polar.

Representation of dipole moment of (c)

Polar, net dipole moment$\ne 0$

d. In the given molecule, the electronegativity value of the given atoms follows the order given below:

$\mathrm{H}\simeq \mathrm{C}<\mathrm{Cl}$

Since the carbon (central atom) has ${\mathrm{sp}}^2$ hybridization, the molecule is also planar.

Therefore, the dipole is in the direction of Cl. Here, the net dipole is zero due to the equal and opposite effect of two dipoles toward Cl. Hence, the molecule is nonpolar.

Representation of dipole moment of (d)

Nonpolar, net dipole moment = 0