Alcohols Flashcards
What is the general formula of alcohols?
CnH2n+2 O
What 3 types of alcohols are there?
Primary
Secondary
Tertiary
What is the most stable type of alcohol?
Tertiary
Made via a tertiary carbocation
What 3 things affect the melting/boiling point of alcohols?
Number of H bonds each molecule can make
Number of e- (strength of LDF)
Surface area of contact
Are alcohols soluble?
Yes, can form H bonds with water
What affects the solubility of alcohols?
Number of H bonds the molecule can form (more H bonds=more soluble)
Length of non polar section
What affects viscosity of alcohols?
Number of H bonds it can make (more H bonds, stronger IMF, More viscous)
Why do alcohols burn more completely than alkanes?
They contain oxygen so less oxygen is needed to make it burn completely.
What is the functional group isomer of alcohols?
Esters
What have higher boiling points, alcohols or esters?
Alcohols as H bonds are stronger than esters
What is used to oxidise alcohols?
Acidified potassium dichromate (VI)
H+/K2Cr2O7
What do you observe when alcohols are oxidised?
Solution goes from orange to green
Why does the solution go from orange to green when alcohols are oxidised?
Chromium is reduced so turns green and this is what proves that alcohols are oxidised
What type of alcohols aren’t oxidised?
Tertiary
What type of alcohols are oxidised the quickest?
Primary
What is dehydration?
Removal of water
What is used in dehydration of alcohols?
Concentrated H3PO4
What 2 things are made in dehydration of alcohols?
Alkene and water
What type of reaction is dehydration?
Elimination
What is made when a primary alcohol is oxidised and heated and distilled?
Aldehyde and water
What is made when a primary alcohol is oxidised and heated under reflux?
Carboxylic acid and water
What is made when an aldehyde is oxidised and heated under reflux?
Carboxylic acid
What is made when a secondary alcohol is oxidised and heated under reflux?
Ketone and water
What is the definition of reflux?
Continuous evaporation and condensation of a volatile substance without the loss of any product to prevent the liquid boiling dry
How many moles of oxidising agent do you need when turning a primary alcohol into a carboxylic acid?
2 as 2 oxidising reactions occur
What is the distillate when oxidising and heating and distilling a primary alcohol?
The aldehyde produced by distillation
Why is heating under reflux better than heating and distilling for secondary alcohols?
Ensures all reactants are turned into products
Which do you use to work out the maximum amount of moles of products, excess or limiting?
Limiting
How do you work out the limiting reactant?
Molar ratio reactants
Do moles divided by ratio, smallest number is limiting.
Once you know limiting reactant how do you work out the maximum amount of moles of products?
Molar ratio limiting to product
Moles of limiting/ratio of limiting X ratio of product
Definition/equation for percentage yield
(Amount of product / Theoretical amount of product)
X100
What does percentage yield tell you?
How efficient a reaction is
What is the problem with percentage yield?
Doesn’t take into account for the waste products
What is the definition for atom economy?
(RFM of desired products / Sum of RFM’s of all products)
X100
What is the atom economy in addition reactions?
100% all the time!
How do you increase atom economy?
FInd other uses for waste products - no longer waste
Change an atom in waste to atom in same group with lower RFM
What are some examples of waste products that could have other uses?
HCl - dissolved in water and bottled to make acid - sold to schools
NaCl - make table salt
CO2 - fizzy drinks, fire extinguishers
Can water be used to stop it being waste?
No, too common so is always waste
What equipment do you need for H.U.R?
Metal clamp stand Clamp Heat Round bottomed flask Condenser Water tap Anti-bumping granules Rubber tubing
What equipment do you need for heat and distil?
Same as reflux AND Still head 3 clips 2 clamp stands (instead of 1) Thermometer Screw tap adapter Reciever
How do you work out the aqueous layer in the separating funnel?
Add water, aqueous layer will get bigger
How do you remove the acid impurities in the separating funnel?
Add a carbonate
Will fizz if H+ is present
Turn upside down and release gas
Repeat until doesn’t fizz
What happens to the organic and aqueous layers in the separating funnel after acid impurities have been removed?
Run off 2 separate layers into separate beakers.
Keep organic layer
After separating organic layer from aqueous layer what do you do?
Dry the liquid using an anhydrous salt
What are the three anhydrous salts?
CaCl2 - hydrocarbons
CaSO4 - General drying
MgSO4 - General drying
When do you stop adding anhydrous salt?
Until there are no lumps/until a fine powder
After drying organic product what do you do?
Decant/filter off liquid
Redistil (specific temperature to remove other organic products)
