5.3.1 Alcohols Flashcards
What are alcohols?
Organic molecules containing an -OH functional group
What is the structure of the name of an alcohol?
The start shows how many carbon atoms. The end is “ol” to show it is an alcohol
What is the molecular and structural formula of methanol?
CH4O and CH3OH
What is the molecular and structural formula of ethanol?
C2H6O and CH3CH2OH
What is the molecular and structural formula of propanol?
C3H8O and CH3CH2CH2OH
What is the molecular and structural formula of Butanol?
C4H10O and CH3CH2CH2CH2OH
What are two industrial methods for ethanol manufacture?
- Hydration of ethene
- Fermentation of glucose
What occurs in hydration of ethene?
Ethene (C2H4) gas is mixed with steam (H2O)
What are conditions for hydration of ethene?
- 300 degrees C
- 65 atm pressure
- Phosphoric acid (H3PO4) catalyst
What are raw materials for ethene hydration?
Crude oil provides ethene
What are advantages to ethene hydration?
- Makes pure ethanol
- Can run continuously
What are disadvantages of ethene hydration?
- Conditions require lots of energy
- Non-renewable raw material used
What happens in fermentation of glucose?
Glucose (C6H12O6) is fermented microbiologically by anaerobic respiration of yeast
What are conditions of fermentation of glucose?
- Yeast
- 30 degrees C
- Anaerobic
What are raw materials of fermentation of glucose?
Sugar cane provides the glucose
What are advantages of fermentation of glucose?
- Renewable raw material used
- Conditions not energy-intensive
What are disadvantages of fermentation of glucose?
- Makes impure ethanol
- Must be done in individual batches
What 3 ways can ethanol be oxidised?
- Combustion
- Microbial Oxidation
- Chemical Oxidation
What occurs in ethanol combustion?
Ethanol usually combusts completely because of the oxygen tom in the -OH group. This results in a non-luminous, blue flame:
C2H5OH + 3O2 –> 2CO2 + 2H2O
What happens in ethanol microbial oxidation?
Micro-organisms, such as bacteria and fungi use the oxygen in air to oxidise ethanol into ethanoic acid. This can only happen aerobically:
C2H5OH + 2[O] –> CH3COOH + H2O
What happens in ethanol chemical oxidation?
Ethanol is heated with:
- potassium dichromate (VI) (K2CrO7)
- dilute sulphuric acid (H2SO4)
C2H5OH + 2[O] –> CH3COOH + H2O
As this occurs, the orange dichromate(VI) ions turn to green chromium(III) ions, this means that there is a colour change:
orange –> green
