IMF

Question 1

Describe the bonding in non-polar molecules

Answer 1

Simple molecular structure and is non-polar, weak IDID interactions exist bt the molecules

Question 2

2 factors affecting the strength of IDID

Answer 2

1. Size of electron cloud
   -larger electron cloud more easily distorted -> easily polarised
   => easier to form partial charges therefore stronger IDID
2. Surface area for molecular interaction
   - same electron cloud size
   - more extensive and stronger in molecules with larger surface area for interactions

Question 3

How is PDPD formed?

Answer 3

• polar molecules
• permanent separation of partial charges
• stronger than IDID if both had same electron cloud size

Question 4

2 criteria to form Hydrogen bonds

Answer 4

1. H atom must be bonded directly to a small and highly electronegativity atom F,O,N (protonic hydrogen)
2. At least one lp of electrons present on a highly electronegative atom (F,O,N)

Question 5

2 factors affecting strength of hydrogen bonding

Answer 5

1. Dipole moment
   - greater differences in electronegativity, larger dipole moment
2. Extensiveness of hydrogen bonding
   - more hydrogen bonds, the stronger the bonding

Question 6

Describe hydrogen bonding in water

Answer 6

1. Each water molecule form 2 hydrogen bonds PER MOLECULE with neighbouring water molecules
2. Ice, water can form up to 4 hydrogen bonds PER MOLECULE with neighbouring water molecules
   - > very open and regular tetrahedral arrangement

Question 7

Dimerisation

Answer 7

• in organic solvents, undergoes dimerisation through formation of H. Bonds bt 2
• watered each acid molecule is surrounded by water molecules -> form hydrogen bonds with water molecules

Question 8

Solubility

Answer 8

1. Non-polar dissolved non-polar solvents
2. Polar dissolve in polar solvents

Energy released in forming solute-solute solvent is sufficient to overcome the solute-solute interactions and solvent-solvent interactions

Question 9

How does intrahydrogen bonding affect the melting point?

Answer 9

• Intrahydrogen bond is formed due to the proximity of a and b groups
-> reduces the extent of intermolecular H bonding
=> the intermolecular forces bt a and b molecules will be predominantly IDID

• if a and b are far apart for intramolucular bonding
-> more extensive intermolecular H bonding