Halogenalkanes 15.1 Flashcards
Nucleophile
Electron pair donor
Why do halogenalkanes have a polar bond?
Halogens are more electronegative than carbon so they have a higher tendency to attract pair of electrons to themselves in a covalent bond. This lead to a polar bond.
Electronegativivity
the ability of a bonded atom to attract a pair of electrons to itself within a covalent bond.
What happens to haloalkanes as you go down the group?
Haloalkanes become more reactive as you go down the group and is hydrolysed the fastest. This means C-I is easier to break and is hydrolysed the fastest.
Why does the reactivity of the haloalkanes increase as you go down the group?
The bond enthalpy and polarity decreases.
Why are fluoroalkanes unreactive?
A large quantity of energy is required to break the C-F bond
Hydrolysis
Splitting of a molecule into two using water. Produces alcohol
Iodide ion precipitate
Yellow precipitate (concentrated + dilute ammonia doesn’t dissolve)
Bromide ion
Cream precipitate (conc ammonia dissolves it)
Chloride ion
White precipitate (dilute ammonia)
How to test for halide ions
Add 2 cm3 of AgNO3 then add dilute nitric acid.
How do you measure the rate of hydrolysis
- Start stopwatch after adding nitric acid, measure the time taken for precipitate to appear.
What do CFC do to the ozone ?
Break the ozone layer.
How are CFCs broken down?
Through UV radiation (iniation)
CFCs aren’t always responsible for ozone depletion, what do nitrogen oxide radicals cause
Nitrogen oxide radicals cause the breakdown of ozone by a mechanism similar to that involving chlorine radicals.
Propagation Step 1 NO• + O3 -> NO2• + O2
NO2• + O —> NO• + O2
Overall : O3 + O —-> 2O2
