alcohols Flashcards
1
Q
functional group alcohols
A
OH
(similar chemical properties)
2
Q
general formula of alcohols
A
CnH2n+1OH
3
Q
ethanol uses
A
- fuels - biofuel for cars
- solvent - perfumes/varnishes
- alcoholic drinks
4
Q
combustion of ethanols
A
C2H5OH + 3O2 > 2CO2 + 3H2O
(oxidation)
burns with clean blue flame
5
Q
oxidation of ethanol methods
A
- combustion
- microbial oxidation
- heating with potassium dicromate and dilute H2SO4
6
Q
ethanol formula
A
C2H5OH
7
Q
ethanol microbial oxidation
A
- microbes use oxygen in air to oxidise alcohols
ethanol + oxygen > ethanoic acid + water
(ethanoic acid = CH3COOH)
8
Q
heating ethanol with an oxidising agent (K2Cr2O7 and H2SO4)
A
- oxidised to a carboxylic acid
- won’t happen unless H2SO4 is added
- goes orange to green
CH2CH3OH + [O] > CH3COOH
[O] is oxidising agent
9
Q
making ethanol
A
- fermentation of glucose
- hydration of ethene
10
Q
fermentation
A
uses enzymes in yeast
glucose > ethanol + carbon dioxide
C6H12O6 > 2C2H5OH + 2CO2
conditions: anaerobic, 30°, 1atm
11
Q
fermentation cannot produce more than 15% ethanol
A
ethanol will kill the yeast if higher (toxic)
to get pure ethanol use fractional distillation
12
Q
hydration of ethene
A
- ethen obtained by cracking of crude oil fractions and hydrated
ethene + steam> ethanol
conditions: 300°, 70atm, phosphoric acid(catalyst)
13
Q
fermentation advantages
hydration disadvantages
A
- renewable
- low cost
- little energy used
14
Q
fermentation disadvantages
hydration advantages
A
- batch - less convenient (not continuous)
- high labour cost
- slow
- not pure
- space needed to grow crops
