Q. 6.108 - An Introduction to General, Organic, and Biological Chemistry

Question

Identify the major intermolecular forces between each of the following atoms or molecules: ($6.9$)

a. data-custom-editor="chemistry" $\mathrm{He}$

b. $HBr$

c. $Sn{H}_4$

d. data-custom-editor="chemistry" ${\mathrm{CH}}_3-{\mathrm{CH}}_2-{\mathrm{CH}}_2-\mathrm{OH}$

Step-by-Step Solution

Answer

(a) The major intermolecular force in $\mathrm{He}$ is dispersion forces

(b) The major intermolecular force in $\mathrm{HBr}$ is a dipole-dipole interaction

(c) The major intermolecular force in ${\mathrm{SnH}}_4$ is dispersion forces

(d) The major intermolecular force in ${\mathrm{CH}}_3-{\mathrm{CH}}_2-{\mathrm{CH}}_2-\mathrm{OH}$ is hydrogen bonding

Part (a) Step 1: Given information

We need to find the major intermolecular force in $\mathrm{He}$

Part (a) Step 2: Explanation

Because the electronegativity of helium atoms is the same, there are no persistent dipoles between them.

As a result, dispersion forces are the strongest intermolecular force between the molecules.

Part (b) Step 1: Given information

We need to find the major intermolecular force in $\mathrm{HBr}$

Part (b) Step 2: Explanation

We must first determine if the molecule is polar or nonpolar because it is not ionic and does not exhibit hydrogen bonding.

H has an electronegativity of $2.1$, while data-custom-editor="chemistry" $\mathrm{Br}$ has an electronegativity of $2.8$. As a result of the electronegativity difference, each data-custom-editor="chemistry" $\mathrm{H}-\mathrm{Br}$ bond is polar covalent. As a result, the internal dipole of the molecule is:

data-custom-editor="chemistry" ${\mathrm{H}}^{\mathrm{\delta }+}-{\mathrm{Br}}^{\mathrm{\delta }-}$

The whole molecule is polar because there is a net dipole moment in it. As a result, dipole-dipole interactions are the intermolecular force.

Part (c) Step 1: Given information

We need to find the major intermolecular force in ${\mathrm{SnH}}_4$

Part (c) Step 2: Explanation

Sn has an electronegativity of $1.8$, while data-custom-editor="chemistry" $\mathrm{H}$ has an electronegativity of $2.1$. Each individual bond is nonpolar covalent because the electronegativity difference between the elements is $0.3$.

The total molecule is nonpolar since each bond is nonpolar covalent.

Because the molecule is nonpolar overall, dispersion forces are the strongest intermolecular force between the molecules.

Part (d) Step 1: Given information

We need to find the major intermolecular force in ${\mathrm{CH}}_3-{\mathrm{CH}}_2-{\mathrm{CH}}_2-\mathrm{OH}$

Part (d) Step 2: Explanation

It's worth noting that the molecule has an $\mathrm{H}-\mathrm{O}$ bond. As a result, the molecule has hydrogen bonds.

As a result, hydrogen bonding is the strongest intermolecular force between the molecules.