Studied by 4 peopleWhat is the functional group of alcohols?
-OH
What is the general formula of alcohols?
C(n)H(2n+1)OH
What is the difference between primary, secondary and tertiary alcohols?
Number of methyl groups attached to the carbon atom with the OH group
primary - 1 methyl group
secondary - 2 methyl groups
tertiary - 3 methyl groups
Are alcohols polar or non-polar and why?
They're polar as theres a large electronegativity difference between carbon and oxygen
Why are alcohols water soluble?
The oxygen is very electronegative, so it can hydrogen bond to water molecules
What intermolecular forces do alcohols contain?
Hydrogen bonds and van der waals forces
What are the products when alcohols are burned in air?
Carbon dioxide and water
What type of reaction occurs between alcohols and halogenating agents?
Nucleophilic substitution
What happens in the reaction between alcohols and halogenating agents?
The -OH group is replaced by a halogen, producing a haloalkane
What happens when PCl5 reacts with alcohols?
Produces chloroalkanes, and white steamy fumes that turn damp blue litmus paper red
What is the dehydration (elimination) of alcohols and what is produced?
Alcohol is heated with conc phosphoric acid
1 molecule of water is removed from the alcohol
Alkenes are formed
What types of alcohols can be oxidised?
Primary and secondary can, tertiary can't
Oxidation of primary alcohols
K2Cr2O7
H2SO4
Heat
distil
Produces an aldehyde
Oxidation of aldehydes
K2Cr2O7
H2SO4
Heat
reflux
produces carboxylic acids
Oxidation of secondary alcohols
K2Cr2O7
H2SO4
Heat
Reflux
Produces a ketone
What is the symbol for potassium dichromate ( vi)?
K2Cr2O7
What is potassium dichromate used as?
Used as the oxidising agent in the oxidation of alcohols
What is the colour change when an alcohol is oxidised with potassium dichromate?
Orange to green
Reaction of alcohol and carboxylic acid
Heat
Reflux
c.H2SO4
Ester + water
What happens in the reaction of haloalkanes and aqueous alkali?
produces alcohols
Nucleophilic substitution
Hydroxide ion acts as a nucleophile
What happens in the reaction of haloalkanes and ethanolic potassium hydroxide?
produces allenes
Elimination reaction
Hydroxide ion acts as a base
What happens in the hydrolysis of haloalkanes with silver nitrate?
water acts as a nucleophile
Alcohol forms
Halide ions released into solution and react with silver ions to form silver precipitates
What colour silver precipitate does each halide ion form?
AgCl - white
AgBr - cream
AgI - yellow
Compare and explain the rates of precipitate formation of the haloalkanes
reactivity depends on strength of C-X bond
Bond strength decreases down group
Rate increases down group
Faster rate = less stable haloalkane
Iodoalknes are fastest, then bromo, then chloro
What is a nucleophile?
Electron pair donor
What are nucleophiles attracted to?
Delta + regions of molecules
What are CFCs?
Chlorofluorocarbons - haloalkanes containing carbon, chlorine and fluorine atoms only
What issue is uv radiation causing?
Ov in the upper atmosphere can cause CFCs to produce halogen radicals which catalyse the breakdown of the Earth's protective ozone layer
Describe heating under reflux
reflux apparatus continually heats the contents of the flask
Condenser ensures vapours condense and return to flask for further heating, ensures product vapours can't escape
Describe distillation
distillation apparatus is used to separate liquids with different boiling points
Round bottomed flask is heated, liquid with lower boiling point will evaporate first, rise into attached tubing surrounded by a condenser which cools and condenses vapour into liquid which is collected in a separate flask
What is a separating funnel and how does it work?
separates 2 liquids with different densities
Mixture added to flask, flask is stoppered and inverted to mix contents
Liquids separate into 2 layers
Open tap to collect bottom denser liquid in 1 flask and then collect 2nd in a separate flask
How can you test the purity of a substance?
Determine the boiling point and compare it to a data book value.
How can you determine the boiling point of a substance?
pack it into a thiele tube with an inverted capillary tube inside
Substance is healed to above boiling point and allowed to cool
When it condenses into a liquid it's drawn into the capillary tube and the temperature where this occurs is the boiling point
Note
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