Intermolecular Forces

Question 1

what is hydrogen bonding?

Answer 1

intermolecular bonding between molecules containing N, O or F and the hydrogen atom of -NH, -OH or HF

Question 2

what are the types of intermolecular forces?

Answer 2

• induced dipole-dipole forces (London forces)
• permanent dipole-dipole forces
• hydrogen bonding

Question 3

which of the intermolecular forces are the weakest?

Answer 3

induced dipole-dipole forces

Question 4

what are permenant dipole-dipole interactions(van der Waals)?

Answer 4

there is a weak electrostatic force of attraction between the delta positive and delta negative molecules

Question 5

what are the anomalous properties of H2O?

Answer 5

• liquid water is denser than solid
• its relatively high melting and boiling points

Question 6

what are the anomalous properties of H2O based on?

Answer 6

results from hydrogen bonding between water molecules

Question 7

why is ice less dense than water?

Answer 7

• hydrogen bonds hold water molecules in solid ice in an open lattice structure
• water molecules are held apart in ice by hydrogen bonds
• solid ice is therefore less dense than water and floats

Question 8

why does water have a relatively high mp and bp?

Answer 8

• water has relatively strong hydrogen bonds which need to be broken
• lots of energy is required to overcome these hydrogen bonds

Question 9

why is hydrogen bonding able to occur?

Answer 9

lone pairs on the N,O or F

Question 10

why would NH3 have a lower boiling point than H2O?

Answer 10

• NH3 has weaker hydrogen bonds than water
• N has 1 lone pair and oxygen has 2 lone pairs