5.3 Organic 2 Flashcards
(28 cards)
what is an alcohol
organic molecules containing an -OH functional group
what does the name of an alcohol tell you
the start shows how many carbon atoms it has
the end is -ol to show it is an alcohol
first few alcohols
CH3OH - Methanol
C2H5OH - Ethanol
C3H7OH - Propanol
C4H9OH - Butanol
where do you draw the OH on an alcohol
they can be attached anywhere in the carbon chain
if they are in the middle, we include a number to see where it is attached
e.g. Propan-1-ol
which categories of formula are used to show alcohols
molecular
displayed
structural
two methods of manufacturing ethanol
hydration of ethene
fermentation of glucose
hydration of ethene process
ethene is mixed with steam under these conditions:
- 300 degrees C
- 65 atm pressure
- phosphoric acid as a catalyst
raw material - crude oil provides the ethene
advantages - makes pure ethanol, can run continuously
disadvantages - conditions require a lot of energy, non-renewable raw material is used
fermentation of glucose process
glucose is is fermented microbiologically under these conditions:
- yeast (provide enzymes)
- 30 degrees c (optimum temp for enzymes)
- anaerobic (no air to prevent oxidation)
raw material - sugar cane provides the glucose
advantages - renewable raw material used, conditions don’t require much energy
disadvantages - makes impure ethanol, must be done in individual batches
3 ways to oxidise ethanol
combustion
microbial oxidation
chemical oxidation
combustion of ethanol process
tends to combust completely due to the oxygen atom in the -OH group
results in a luminous, blue flame
microbial oxidation of ethanol process
many micro-organisms, like bacteria and fungi, can use oxygen in the air to oxidise ethanol into ethanoic acid
this can only happen aerobically
we can represent the microbial use of oxygen in an equation using the [O] symbol
chemical oxidation of ethanol process
heat it with a mixture of potassium dichromate and dilute sulfuric acid
orange –> green
carboxylic acids
organic molecules with a -COOH functional group
what does a carboxylic acid’s name tell us
the start shows how many carbon atoms it has
the end is ‘-oic acid’ to show it is a carboxylic acid
first few carboxylic acids
HCOOH - Methanoic acid
CH3COOH - Ethanoic acid
C2H5COOH - Propanoic acid
C3H7COOH - Butanoic acid
what is vinegar
an aqueous solution of ethanoic acid
when does vinegar form
when the ethanol in wine undergoes microbial oxidation
what is vinegar like
it has a very sour, acidic taste because of the acidity of ethanoic acid
behaviour as acids
an acid is a H+ donor, so carboxylic acids can donate H+ to form a salt
they lose H+ and become negatively charged
the name changes from -oic acid to oate in the salt
e.g. ethanoic acid –> ethanoate
reactions of carboxylic acid with metals
Acid + metal –> salt + hydrogen
observations: effervescence, solid disappears
e.g. Methanoic acid + sodium –> sodium methanoate + hydrogen
reactions of carboxylic acid with metal carbonates
acid + metal carbonate –> salt + water + carbon dioxide
observations: effervescence, solid disappears
e.g. Methanoic acid + sodium carbonate –> sodium methanoate + water + carbon dioxide
what are esters
a family of organic molecules which form when a carboxylic acid and an alcohol join together by losing an H20 molecule
ester functional group
COO
making esters process
- mix the carboxylic acid and alcohol together
- add concentrated sulfuric acid (catalyst)
- warm
- add the mixture into sodium carbonate solution to neutralise the sulfuric acid catalyst
- wait until fizzing has stopped
