Making Ethanol Flashcards
What are the 3 ways that Ethanol can be produced?
- Fermentation
- From Biomass
- From Ethane and Steam
How does Fermentation make ethanol?
By using yeast to convert sugars into ethanol
What is the word equation for fermentation producing ethanol?
Sugar –(yeast)–> ethanol + carbon dioxide
What acts as a catalyst for fermentation and where is it found?
An enzyme called Zymase, which is found in the yeast cells
What is the optimum temperature for fermentation?
30 degrees celcius
What can’t fermentation be colder or hotter than its optimum temperature?
BEcause if it’s too cold then the reaction slows down, and if its too hot then Zymase will denature
What is the optimum pH for Zymase and why?
pH 4
If it is too acidic or alkali then it will stop working
Why is it important to prevent oxygen getting into the fermentation process?
Because oxygen converts ethanol into ethanoic acid which lowers the pH and can stop the enzyme working
At what concentration does the fermentation reaction stop and why?
10-20%
Because the yeast gets killed off by the ethanol
How is the ethanol solution made from fermentation concentrated?
By distillatin
Describe the process of Distillation with ethanol
- Ethanol is heated in a fractioning column and made to boil so the vapour travels up the column, cooling as it goes
- The temperature is such that anything with a higher boiling point than ethanol cools to a liquid and condenses back to the bottom, meaning that only pure ethanol vapour reaches the top
- It flows into a condenser where it is collected
Will the raw materials for fermentation run out?
Sugar beet grows quickly so it won’t
How good is the atom economy for fermentation?
It has a low atom aconomy because of the waste CO2 produced and the enzyme is killed off by the ethanol, meaning it is less efficient
How are the waste products dealt with after fermentation?
CO2 is released without any processing
What are the energy costs for fermentation?
Energy is needed to maintain the optimum temperature
What effects does fermentation have on the environment?
Cabron Dioxide is a greenhouse gas so it adds to global warming
What are the health and safety risks of fermentation?
There are no specific dangers
What is fermentation’s effect upon society?
Drinking ethanol has an impact
Why can’t waste biomass be fermented in the normal way to make ethanol?
Because it contains a lot of cellulose; yeast cannot convert cellulose into ethanol like it can to sugars
What is used as a substitute for yeast when using biomass to make ethanol?
E. coli bacteria can be genetically modified to do it
What are the optimum conditions for making ethanol using biomass?
35 degrees
pH 6
What is the advantage of using Biomass to make ethanol over using fermentation?
You don’t have to grow crops especially for it, you can just use the waste from other crops
Why is fermentation not used to produce ethanol on a large scale?
Because it is too slow
What process is used to make ethanol on an idustrial scale?
Ethene reacting with steam
Where is Ethane found?
It is one of the hydrocarbons in crude oil and natural gas
What is the word equation for how Ethene is formed? How does it happen?
Ethane —-> Ethene + Hydrogen
Ethane is cracked (split) to form the two products
What is the word equation for how ethanol is produced using ethene?
Ethene + Steam —> Ethanol
What are the optimum conditions for using ethene to produce ethanol and what is the catalyst used?
Temperature: 300 degrees celcius
Pressure: 70 atmospheres
Phosphoric acid
Will the raw materials for the process of making ethanol using ethene run out?
Yes; Crude oil and natural gas are non-renewable
How good is the atom economy for making ethanol using ethene?
The only waste product is hydrogen
How are the waste products dealt with after making ehtanol from ethene?
Hydrogen can be re-used to make ammonia in the Haber process
What are the energy costs for making ethanol using ethene?
Energy is used to maintain the high temperature and pressure
What is the effect on the environment of making ethanol from ethene?
No waste products produced can harm the environment, although getting crude oil can cause oil spills
What are the health and safety risks of making ethanol from ethene?
The high temperature and pressure have to be carefully controlled or it would be very dangerous
