OZ 6- The CFC Story

Question 1

What are CFC’s?

Answer 1

• chlorofluorocarbons
• compounds containing chlorine, fluorine and carbon
• used in refrigerants and aerosols

Question 2

What are halo alkanes (halogenoalkanes)?

Answer 2

When 1 H atom in alkane is replaced with halogen

Question 3

Define electronegativity

Answer 3

An atoms ability to attract electrons in a covalent bond

Question 4

What is the most electronegative atom?

Answer 4

Fluorine

Question 5

What makes a molecule polar?

Answer 5

When 1 atom is more electronegative, attracts electrons in bond more strongly

Question 6

Define permanent dipole

Answer 6

• when there is significant difference in electronegativity in 2 atoms, bond is permanently polarised

Question 7

How can a molecule be non-polar but contain permanent dipoles?

Answer 7

-depends on distribution of electronegativity

Question 8

Define instantaneous dipole

Answer 8

When a non-polar molecule becomes polar, because the elctrons in a bond are not evenly distributed. Happen to move closer to 1 atom

Question 9

Define induced dipole

Answer 9

When an unpolarised molecule is next to a dipole, the partially negative end will attract the positive end and cause movement of electrons

Question 10

Which is the strongest kind of intermolecular force (except H bonds)?

Answer 10

Permanent dipole-permanent dipole

Question 11

What is the weakest type of intermolecular force?

Answer 11

Instantaneous dipole-induced dipole

Question 12

Does branching in alkanes affect mp and bp?

Answer 12

Yes-more branching less points of contact for IM forces, more easily broken

Question 13

What are chlorine reservoir molecules and what do they do?

Answer 13

• when molecules react with chlorine radicals in atmosphere, and store chlorine.
  CH4 + Cl. CH3 + HCl
  NO2 + ClO ClONO3