Topic 3.2

Question 1

What are secondary interactions/forces?

Answer 1

weak interactions between atoms caused by partial charges

Question 2

Difference between intermolecular and intramolecular attraction?

Answer 2

Intermolecular is between molecules. Intramolecular is between atoms in a molecule.

Question 3

Name the 3 secondary forces

Answer 3

Dispersion force, dipole-dipole, hydrogen bonding

Question 4

What is the weakest type of interaction?

Answer 4

dispersion force

Question 5

Does dispersion force occur between polar or nonpolar molecules?

Answer 5

nonpolar

Question 6

What causes dispersion force?

Answer 6

Caused by temporary fluctuations in the electron distribution of atoms and molecules which creates dipoles that induce similar fluctuations in other molecules/atoms and attracts them.

Question 7

Would a molecule with more surface area have a stronger secondary force than a smaller molecule?

Answer 7

yes

Question 8

Explain why N2 has a low boiling point

Answer 8

N2 is a nonpolar molecule that operates dispersion force, the weakest secondary force. Low energy is required to disrupt this force.

Question 9

State and explain whether H2 has a lower or a higher boiling point than N2.

Answer 9

H2 is less polar than N2. N2 operates a stronger dispersion force than H2. More energy would be required to disrupt the force of N2 than H2. H2 has a lower boiling point than N2.

Question 10

State and explain whether butane or isobutane has a higher bp (butane has a straighter structure).

Answer 10

Butane has a straighter structure than isobutane , meaning it has a larger surface area to operate stronger dispersion force than isobutane. More energy would be required to disrupt the force of butane than isobutane. Butane has a higher boiling point.

Question 11

Explain dipole-dipole force

Answer 11

Occurs between polar molecules, and has attraction force between distinct positive and negative ends.

Question 12

Is hydrogen bonding weaker than dipole-dipole force?

Answer 12

no

Question 13

Hydrogen bonding occurs between hydrogen atom bonded to —–?

Answer 13

N, O, F

Question 14

True or false: Hydrogen atom has to interact with a lone pair of electrons on another N, O, F atom in a polar molecule

Answer 14

true

Question 15

Explain why H2O has a higher boiling point than H2S.

Answer 15

H2O is a more polar molecule than H2S. The hydrogen bonding force of h2o is stronger than the dipole-dipole force operating in h2s. H2O needs greater amount of energy to be disrupted, thus it has a higher bp.

Question 16

Explain why SO3 (nonpolar) has a higher bp than SO2 (polar)

Answer 16

Although SO2 is a polar molecule and SO3 is nonpolar, SO3 has a higher bp. The trigonal planar shaped SO3 molecule operates a stronger dispersion force than the dipole-dipole force of the bent-shaped SO2 molecule. More energy would be required to disrupt the forces in SO3 compared to SO2.