alcohols Flashcards
what is the functional groups of alcohols?
-OH
what is -OH connected to and how?
it is covalently bonded to a carbon chain
what is the formula of ethanol?
C2H5OH
(CH3CH2OH)
what is the molecular formula of methanol?
CH4O
what is the molecular formula of ethanol?
C2H6O
what is the molecular formula of propan-1-ol?
C3H8O
what is the molecular formula of butan-1-ol?
C4H10O
what is the structural formula for methanol?
CH3OH
what is the structural formula for ethanol?
CH3CH2OH
what is the structural formula for propan-1-ol?
CH3CH2CH2OH
what is the structural formula for butan-1-ol?
CH3CH2CH2CH2OH
draw out the displayed formula for the first 4 alcohols. what are their names?
check p.288 for reference
methanol, ethanol, propan-1-ol, butan-1-ol
what does each part of the word methanol tell you?
meth - number of carbon atoms
an - molecules are saturated (NO DOUBLE CARBON BONDS)
ol - there is an -OH functional group
what does the 1 in propan-1-ol tell you?
it tells you where the -OH group is in the carbon chain
what are propan-1-ol and propan-2-ol?
structural isomers
what happens when alcohols burn?
they from carbon dioxide and water
what is the equation for ethanol burning?
C2H5OH(l) + 3O2(g) -> 2CO2(g) + 3H3O(l)
what is ethanol?
it is a bioful
what is a biofuel?
a fuel that is made from biological sources, such as sugar cane or corn
what happens when an alcohol is left in air?
it is oxidised by the air in the presence of microbes (microbial oxidation)
what happens to ethanol when it is left in air?
it is oxidised by the help of microorganisms such as bacteria or yeast to form ethanoic acid
what is the formula for ethanoic acid?
CH3COOH
name a way in which ethanol can be oxidised? (in a lab)
it can be oxidised by heating with potassium dichromate (VI) in dilute sulfuric acid.
1. the oxidising agent is a mixture of potassium dichromate (VI) and dilute sulfuric acid. it is a strong oxidising agent with the formula K2Cr2O7. the sulfuric acid is important for the potassium dichromate (VI) to act as an oxidising agent
2. a few drops of ethanol are added to a solution containing the orange mixture of potassium dichromate (VI) and dilute H2SO4 in a test tube.
3. heat the tube in A HOT WATER BATH
4. the solution turns green and now contains a very dilute solution of ethanoic acid together with other products.
5. the green colour 9indicated the precense of Cr3+ ions, which are formed when potassium dichromate (VI) is reduced.
the product also smells like vinegar (an acid)
what do you need to do to stay safe when oxidising ethanol in a lab?
- wear eye protection
- add the reaction very slowly to prevent too violent a reaction
- do not point the mouth of the test tube towards you as the contents may spit out
what are the conditions required to oxidising ethanol in a lab?
heat under reflux
draw a diagram of what oxidising ethanol in a lab might look like?
p.290
what is the formula for potassium dichromate (VI)
K2CrO7
what is potassium dichromate (VI) in the reaction when oxidising ethanol in a lab?
the oxidising agent. it itself is reduced
what is the half equation of what happend to the chromium
Cr2O7 (2-) -> Cr (3+)
charge on chromium ion goers from 6+ on the left hand side to 3+ on the right hand side
(don’t ask how idk)
what is the colour change that takes place when oxidising ethanol in a lab?
it goes from orange to green
what is refulx?
when you heat something and you stop vapour from escaping
write an equation for the oxidation of ethanol into ethanoic acid using displayed formula
p 290 or look in book
(structural formula: С2H5OH + 2 [O] -> CH₃COOH + H20. )
what is the structual equationfor the oxidation of ethanol into ethanoic acid
С2H5OH + 2 [O] -> CH₃COOH + H20
in a reaction where butanoic acid has been formed, how would you show it had been formed?
use universal indicators. it shows it is acidic. it would turn orange or red
what is the equation for fermentation? - symbol
C6H12O6 (aq) -> 2C2H5OH(aq) + 2CO2(g)
what is the equation for hydration of ethene? - symbol
H2O (g) + CH2=CH2 (g) -> CH3CH2OH(g)
what is the equation for fermentation? - word
glucose -> ethanol + carbon dioxide
what type of reaction is hydration of ethene?
continuous flow (stream of reactants constantly passed over catalyst)
what conditions are required for hydration of ethene?
300 degrees celcius
60-70 atm (pressure)
what is the catalyst for hydration of ethene?
phosphoric acid (H3PO4)
what are the starting materials in fermentation?
they are non-renewable (from crude oil)
what type of reaction is hydration of ethene?
quick
what is the purity of hydration of ethene?
very pure ethanol
what is the equation for hydration of ethene? - word
ethene + steam -> ethanol
what type of reaction is fermentation?
batch
what conditions are required for fermentation?
30 degrees celcius
anaerobic conditions
what is the catalyst for fermentation?
enzymes in yeast
what are the starting materials in fermentation?
they are renewable (sugar beet or sugar cane)
what type of reaction is fermentation?
slow - several days per batch
what is the purity of fermentation?
impure ethanol (less than 15%)
what are two types of producing ethanol?
fermentation (of sugar), hydration of ethene
why can’t more than 15% alcohol be produced in a mixture in fermentation of sugar?
the yeast is killed by more than 15% alcohol
how can alcohol made by fermentation be separated?
it can be purified using fractional distillation (as ethanol (78 degrees) and water (100 degrees) have different boiling points
what happens suring the hydration of ethene?
ethanol is made by reacting ethene with steam (hydration).
only a small proportion of ethene reacts. the ethanol produced id condensed as a liquid and the unreacted ethene is recycled through the process.
pros and cons for fermentation
pros:
uses renewable resources
uses gentle temperatures and atmospheric pressure (less energy requires, hence less expensive)
cons:
batch process (inefficient)
slow reaction
produces impure ethanol which needs further processing
pros and cons for hydration of ethene?
pros:
- continuous flow process (a steam of reactants is constantly passed over the catalyst - more efficient than a batch process
- quick
- produces much purer ethanol
cons:
- uses finite resources
- uses high temp and pressures requiring a high energy output
why does fermentation occur in the conditions that it does?
**in absence of air: **Fermentation is conducted in the absence of air. In the presence of air (aerobic conditions), enzymes in the yeast produce carbon dioxide and water instead of ethanol. Also, in the presence of air, the ethanol can oxidise to ethanoic acid.
at 30 degrees: Above 40⁰ the enzymes would permanently lose their structure (denature).
At a temperature lower than 30⁰ the process would be too slow.
what is another name for yeast?
zymase
what type of reaction is fermentation (e.g., addition, substitution etc.)
decomposition
what type of reaction is the hydration of ethene (e.g., addition, substitution etc.)
addition
why is a continous process good?
more efficient
what is an example of glucose
sugar cane or sugar beet
what is the formula for phosphoric acid?
H3PO4
ethene is stored under pressure and passed through a pipe into a container when used to ripen bananas. name one risk of doing this
may explode or leak due to pressure
Which type of fat contains a double carbon to carbon (C C) bond?
unsaturated fats
Which type of fat contains a double carbon to carbon (C C) bond?
unsaturated fats
