C14- Alchols Flashcards
(48 cards)
What does anhydrous mean?
Containing no water molecules
What is an elimination reaction?
The removal of a molecule from a saturated molecule to make an unsaturated molecule.
What is dehydration?
An elimination reaction in which water is removed from a saturated molecule to make an unsaturated molecule.
What does unsaturated mean?
Contains a multiple carbon-to-carbon bond.
What does saturated mean?
Containing single bonds only.
What are polar molecules?
A molecule with an overall dipole, having taken into account any dipoles across bonds and the shape of the molecule.
What is a primary alcohol?
An alcohol in which the -OH group is attached to a carbon atom that is attached to a two or three hydrogen atoms.
What is a secondary alcohol?
An alcohol in which the -OH group is attached to a carbon atom that is attached to two carbon chains and one hydrogen atoms.
What is a tertiary alcohol?
An alcohol in which to -OH group is attached to a carbon atom that is attached to no hydrogen atoms.
What is an substitution reaction?
A reaction in which one atom or group of atoms is replaced by another atom or groups of atoms.
Why are alcohols generally polar?
Due to the electronegative hydroxyl group which pulls the electrons away fro, the carbon to the Oxygen.
How can hydroxyl group -OH form hydrogen bonds?
The oxygen molecule draws electron density away from the hydrogen giving the hydrogen a slightly positive charge. This positive charge can attract lone pairs from a neighbouring oxygen molecule and form hydrogen bonds.
What are the three properties the alcohols have due to the fact that their -OH can form hydrogen bonds?
- Soluble in water
- increase in the size of the alcohol decreases the solubility of it
- Low volatility compared with alkanes
Why are (small) alcohols soluble in water?
Alcohols and water form hydrogen bonds between the -OH and H2O, this hydrogen bonding allows it to mix freely with water - so it’s soluble.
Why is it when the alcohols increase in size that their solubility in water decreases?
In larger alcohols, most of the molecules are non-polar (the carbon chain with hydrogen), so there is less attraction for the H2O molecules as the alcohol increase in size.
Why do alcohols have a low volatility compared with alkanes?
Alcohols also form hydrogen bonds with each other. Hydrogen bonding is the strongest type of intermolecular force so they have a low volatility (don’t evaporate easily into a gas).
Explain the combustion (burning) of alcohol?
Alcohols burn completely in a plentiful supply of oxygen to produce carbon dioxide and water.
Write the full equation for the combustion of ethanol?
C2H5OH (l) + 3 O2 (g) —> 2 CO2 (g) + 3 H2O (l)
What is another way alcohols can by oxidised without combustion?
An oxidising agent
What are some examples of oxidising agents used in the oxidation of alcohols?
Acidified potassium dichromate - K2Cr2O7
Dilute Sulfuric acid - H2SO4
When is an alcohol completely oxidised?
When all the C-C and C-H bonds are broken.
Happens in the combustion of alcohol but not with the oxidising agent which mildly oxidise alcohols.
If alcohol is oxidised with dichromate what is the equation and what ions are reduced?
Cr2O7 2- —> Cr 3+
Orange solution dichromate (VI) ions is reduced to a green solution containing chromium (III) ions.
What is Reflux?
The continual boiling and condensing of a reaction mixture back to the original container to ensure that the reaction takes place without the contents of the flask boiling dry.
What is distillation?
Distillation is the process of separating the components or substances from a liquid mixture by using selective boiling e condensation
