Physical properties

Question 1

Alkanes mp/bp?

Answer 1

Low boiling and melting points
- Alkanes have simple molecular structures.
- Low amount of energy needed to overcome the weak
intermolecular instantaneous dipole-induced dipole attractions.

Question 2

Alkane mp bp comparison (branching)

Answer 2

branching lowers the boiling points. Both compounds have simple
molecular structures.

Answering technique:
1. State which has a straight chain and which has a branched
chain.
2. Extent of surface area of contact
3. Extent of distortion of the electron cloud
4. Extent of intermolecular instantaneous dipole-induced dipole
attractions
5. Energy requirement

Question 3

Solubility of Alkanes

Answer 3

Alkanes are soluble in non-polar organic solvents.
Reason:
Instantaneous dipole-induced dipole attractions between alkane
molecules and nonpolar solvent molecules result in the release of
sufficient energy to overcome the instantaneous dipole-induced dipole
attractions between the alkane molecules and that between the non-polar solvent molecules.

Question 4

Chemical properties of alkanes

Answer 4

Alkanes are generally unreactive as:
● they are saturated and non-polar. Alkanes do not contain any
region of low or high electron density and thus are unreactive
towards polar reagents.
● the C–C or C–H bonds are strong

Question 5

Physical properties of enantiomers

Answer 5

They have
identical physical and chemical properties except that they rotate
plane polarised light in opposite directions. They have different biological properties due to the shape determining how it interacts with biological molecules (enzymes)

Question 6

Physical properties of TM?

Answer 6

• hard and high densities
• high mp bp
• good conductors of heat & electricity

Question 7

Atomic radius & IE of TM?

Answer 7

Almost constant
- protons increase
- inner 3d electrons shield outer 4s electrons
- increase in shielding offsets nuclear charge increase
HENCE relatively constant

Question 8

MP BP of TM?

Answer 8

Generally higher
- 3d and 4s electrons close in energy
- both 3d and 4s electrons are available for delocalization into sea
- metallic bond is stronger

Question 9

Density of TM?

Answer 9

TM are denser
- smaller atomic size but larger atomic masses !!
- more atoms packed per unit volume

Question 10

Solubility qns answering?

Answer 10

1. Energy released by ION DIPOLE INTERACTIONS between Cl- and H2O
2. Sufficient to overcome the ionic bonding in ___ and hydrogen bonding in H2O
3. Energetically favorable