Effect of the halogen on the reactivity of a haloalkane - OZ

Question 1

What happens to the C-hal bond polarity going down the group

Answer 1

gets less polar because the halogen atom gets less electronegative, so the difference in electronegativity between it and carbon lessens. This makes the carbon less partially positive so nucleophiles will be slower to attack

Question 2

What happens to the C-hal bond strength going down the group

Answer 2

gets weaker because the larger the binding atoms, the further away the bonding electron from the nucleus so the weaker the attraction. This bond has to break when the nucleophile attacks and this bond breaking process gets easier hence faster going down the group

Question 3

Is bond polarity or bond strength more important in the reactivity of a haloalkane

Answer 3

experiments show that bond strength is most important

Question 4

Order of reactivity of haloalkanes

Answer 4

most reactive = C-I, C-Br, C-Cl, C-F = least reactive

Question 5

Experiment to compare the rate of reaction of different haloalkanes - How does it show reactivity

Answer 5

Silver nitrate solution gives an immediate precipitate if added to a solution containing halides, but adding it to a haloalkane will not give a ppt straight away because the haloalkane first has to react with the nucleophile present (water). So when the silver nitrate is added you will time how long it takes for a ppt to appear

Question 6

Method of the experiment to compare the rate of reaction of different haloalkanes

Answer 6

a sample of each haloalkane is put in a test tube with some ethonal and all 3 test tubes are put into the same water bath and left until the temp in all tubes are the same. Then the silver nitrate solution and the timer is started. Time how long it takes for a ppt to appear in each one

Question 7

Results of the experiment to compare the rate of reaction of different haloalkanes

Answer 7

yellow ppt of AgI forms first
cream ppt of AgBr forms second
white ppt of AgCl forms last

Question 8

Why is halobutanes used instead of halomethane in the experiment to compare the rate of reaction of different haloalkanes

Answer 8

because halobutane is a liquid at room temp but halomethane is not

Question 9

Why is ethanol used in the experiment to compare the rate of reaction of different haloalkanes

Answer 9

has haloalkanes are immiscible in water so the ethanol acts as a mutual solvent for the haloalkane, water and silver ions

Question 10

Why is the experiment to compare the rate of reaction of different haloalkanes done it the same water bath

Answer 10

because they all need to be the same temp otherwise the rate of reaction could be affected

Question 11

Which reaction would be quicker when reacted with NaOH, 2-bromopropane or 2-chloropropane and why

Answer 11

2-bromopropane would be quicker because it requires less energy to break the carbon-bromine bond