Chapter 14 - Alcohols Flashcards
What is the comparison of alcohols boiling points with alkanes?
Alcohols have a higher boiling point than alkanes with the same number of C atoms
They are less volatile
Compare the physical properties of alkanes and alcohols
Alkanes are non-polar whereas alcohols are polar
Alkanes have weak London forces between molecules whereas alcohols can form stronger hydrogen bonds between molecules
Alkanes don’t require aa much energy to overcome whereas alcohols require more energy to overcome
What does a low viscosity mean?
Liquid flows easily
Are alcohols soluble in water?
Yes
Greater than alkanes
The -OH group can form hydrogen bonds with water
How does the solubility of an alcohol in water change as the hydrocarbon chain gets larger?
Decreases
The non-polar hydrocarbon chain cannot form hydrogen bonds with water
What is viscocity?
A measure of fluid’s resistance to flow
What does a high viscosity mean?
Liquid doesn’t flow easily
What happens to the viscosity as the number of OH groups increases
Increases
How are alcohols classified?
Primary, secondary or tertiary
Depending upon how many C atoms are attached to the carbon with the OH functional group
What are the oxidation products of a primary alcohol?
Aldehydes (gentle heat distillation)
Carboxylic acids (reflux, high temp)
What are the oxidation products of a tertiary alcohol?
Not oxidised
They do not have a hydrogen atom bonded to the carbon atom
How can the hydroxyl group in some alcohols be oxidised?
By using potassium dichromate (VI) solution (K2Cr2O7) acidified with sulphuric acid (H2SO4)
Observation: Orange to green
What are the oxidation products of a secondary alcohol?
Ketone
What is the carbonyl functional group?
-CHO
Where in an aldehyde is the carbonyl functional group found?
At the end of the hydrocarbon chain
How do we name aldehydes?
Parent chain + suffix “-al”
Where in a ketone is the carbonyl functional group found?
Joined to two carbon atoms in the carbon chain
How do we name ketones?
Parent chain + suffix “-one”
What is the carboxyl functional group?
-COOH
How do we name carboxylic acids?
Parent chain + suffix “-oic acid”
What does a reflux reaction involve practically?
Allows continuous heating of volatile reactants
Vaporised reactants condense and drip back into reaction vessel to continue reaction
What does a distillation reaction involve practically?
Uses a side-mounted condenser to separate liquids according to their boiling points
What is an elimination reaction?
A reaction in which a small molecules is removed from a larger molecule leaving an unsaturated molecule
What is a substitution reaction?
A reaction in which one atom or group of atoms is replaced by another atom or group of atoms
