Chapter 15 Key Concepts Flashcards
What affects the rate of hydrolysis
The strength of the CX bond. The strong the bond the slower the rate of hydrolysis
C-F is strongest
So fluoralkanes are unreactive so a large amount of energy needed to break the CF
C-I is weakest
So iodoalkanes react faster than bromoalkane which react faster than chloroalkanes
How to measure the rate of hydrolysis of primary haloalkanes
Carry out the reaction in the presence of aq silver nitrate
As the reaction occurs X- made that reacts with Ag+ to make the AgX solid ppt
- water from the aq silver nitrate is the electrophile
- haloalkanes are insoluble in water so use an ETHANOL SOLVENT which allows the water and haloalkane to mix to make a single solution not two layers
What are organohalogens and what are they used for
Molecules with at least one H atoms joined to a carbon chain Rarely found it nature and not broken down in the environment Uses -general solvents CHCl3 -dry cleaning solvent C2H2Cl2 and C2HCl3 -making polymers C2H3Cl and C2F4 -flame Retardants CF3Br -refrigerants F2CCl2 HCClF2 HCCl2F
Dangers of UVB
Increased genetic damage
Increased risk on skin cancer in humans
Cataracts
Crop mutation
Why were CFC and HCFC used and what were they used for?
Refrigerants
Aerosol propellants
Air conditioning units
CX bonds makes them very stable so stay in the troposphere for very long…until they reach the stratosphere where UV provides enough energy to break the CCl bond (because it has the lowest bond enthalpy) in photodissociation
Major sources of NO radicals?
Lightning and aircraft travel in the stratosphere
What was good about the whole CFC situation
Acceptance of scientific evidence explaining ozone depletion that led to government legislation against CFC use