4.2.2 Haloalkanes

Question 1

What happens to the polarity when you go from C-F to C-I?

Answer 1

• Polarity decreases.

Question 2

What is the electron deficient carbon susceptible to?

Answer 2

• Attack by nucleophiles.

Question 3

Define nucleophile.

Answer 3

• Electron pair donor.

Question 4

What reaction and chemical is needed to go from a haloalkane to an alcohol?

Answer 4

• Hydrolysis and NaOH.

Question 5

How do you measure the rate of a halogenoalkanes being hydrolysed?

Answer 5

• The halogenoalkane is heated with silver nitrate. Ethanol is also added to act as a solvent. Water acts as a nucleophile.

Question 6

What is the formula for calculating the rate?

Answer 6

• 1/time taken for precipitate to form.

Question 7

What observation can be made for a chloroalkane?

Answer 7

• White ppt.

Question 8

What observation can be made for a bromoalkane?

Answer 8

• Cream ppt.

Question 9

What observation can be made for an iodoalkane?

Answer 9

• Yellow ppt.

Question 10

How do you make measuring the rate at which halogenoalkanes are hydrolysed a valid investigation?

Answer 10

• Use equal moles of haloalkane.
• Use haloalkanes with the same chain length.
• Use a water bath to ensure constant temperature.

Question 11

Out of all the halogenoalkanes, which one reacts the fastest?

Answer 11

• Iodoalkanes.

Question 12

Why do fluoroalkanes not react readily?

Answer 12

• Because they have such a strong bond that they do not react readily.

Question 13

What happens to the bond strength of haloalkanes as the size of the atom increases?

Answer 13

• The bond strength decreases.

Question 14

What does the ozone protect humans against?

Answer 14

• The sun’s UV rays.

Question 15

What does UV rays damage in the human body?

Answer 15

• Damages DNA causing skin cancers.

Question 16

What are the uses of CFCs?

Answer 16

• Coolants in fridges
• Propellants in aerosols
• Degreasing circuit boards
• Dry cleaning solvents.

Question 17

What occurs when UV radiation strikes a CFC molecule?

Answer 17

• It is broken down by homolytic fission to produce a chlorine radical.

Question 18

What happens when a chlorine radical collides with ozone?

Answer 18

• It steals an oxygen atom to form a chlorine monoxide radical and leaves behind an oxygen molecule.

Question 19

What happens when the chlorine monoxide radical collides with a free oxygen atom?

Answer 19

• The two oxygen atoms bond to form an oxygen molecule, leaving behind the chlorine radical which is free to attack more ozone.

Question 20

What are the steps required to purify an organic liquid?

Answer 20

• Use a separating funnel to separate organic and aqueous layers.
• The organic layer sits on top of the aqueous layer.
• Dry the organic layer with an anhydrous salt.
• Re-distil to purify the product at 83 degrees celsius.

Question 21

Why does the organic layer sit on top of the aqueous layer?

Answer 21

• The organic layer is less dense.