alcohols

Question 1

functional group alcohols

Answer 1

OH
(similar chemical properties)

Question 2

general formula of alcohols

Answer 2

CnH2n+1OH

Question 3

ethanol uses

Answer 3

• fuels - biofuel for cars
• solvent - perfumes/varnishes
• alcoholic drinks

Question 4

combustion of ethanols

Answer 4

C2H5OH + 3O2 > 2CO2 + 3H2O
(oxidation)
burns with clean blue flame

Question 5

oxidation of ethanol methods

Answer 5

• combustion
• microbial oxidation
• heating with potassium dicromate and dilute H2SO4

Question 6

ethanol formula

Answer 6

C2H5OH

Question 7

ethanol microbial oxidation

Answer 7

• microbes use oxygen in air to oxidise alcohols
  ethanol + oxygen > ethanoic acid + water
  (ethanoic acid = CH3COOH)

Question 8

heating ethanol with an oxidising agent (K2Cr2O7 and H2SO4)

Answer 8

• oxidised to a carboxylic acid
• won’t happen unless H2SO4 is added
• goes orange to green
  CH2CH3OH + [O] > CH3COOH
  [O] is oxidising agent

Question 9

making ethanol

Answer 9

• fermentation of glucose
• hydration of ethene

Question 10

fermentation

Answer 10

uses enzymes in yeast
glucose > ethanol + carbon dioxide
C6H12O6 > 2C2H5OH + 2CO2
conditions: anaerobic, 30°, 1atm

Question 11

fermentation cannot produce more than 15% ethanol

Answer 11

ethanol will kill the yeast if higher (toxic)
to get pure ethanol use fractional distillation

Question 12

hydration of ethene

Answer 12

• ethen obtained by cracking of crude oil fractions and hydrated
  ethene + steam> ethanol
  conditions: 300°, 70atm, phosphoric acid(catalyst)

Question 13

fermentation advantages
hydration disadvantages

Answer 13

• renewable
• low cost
• little energy used

Question 14

fermentation disadvantages
hydration advantages

Answer 14

• batch - less convenient (not continuous)
• high labour cost
• slow
• not pure
• space needed to grow crops