Hi can u check my response
Is it too long and how do you allocate marks?
Question: 7 marks With reference to the underlying chemistry and with relevant equations, assess the impacts on society of two uses of ethanol
Ethanol is a renewable resource produced by fermentation of sugary crops such as sugar can and corn
C6H12O6(aq) --> 2C2H6O(aq) + 2CO2(g)
Carbon dioxide and water is released when ethanol is combusted hence it is a useful car fuel.
C2H6O(l) + O2(g)--> 2CO2(g) +3H2O(l)
Theoretically, the carbon dioxide released from combustion of ethanol balances with the CO2 absorbed during photosynthesis. Hence, ethanol is considered carbon neutral as it does not lead to increase in CO2 in the atmosphere, thus prevents global warming and has a significant positive impact on society.
However, fossil fuels are used during the farming process, distillation and distribution of ethanol. Hence, it does lead to a net increase in CO2 into the atmosphere. Moreover, production of ethanol requires the clearing of vast areas of arable land which can impact on food production, causes environmental problems like soil erosion and salinity and destructs animal habitats.
Weighing up the pros and cons, using ethanol as fuel has a negative impact on society as it does lead to increase in CO2 when the energy output of its production is taken into consideration which can elevate global warming and in addition it requires clearing of arable land which also leads to severe environmental problems.
Ethanol is also used as solvent for polar substances like water, and non-polar substances like oil and grease. It has non-polar region (-C2H3) which interacts with the non-polar substances via dispersion forces and also has a polar-region (OH-) which forms hydrogen bonds or dipole-dipole interact with polar substances.
(including a diagram of ethanol bonding with polar/non-polar sub)
Therefore, ethanol is used as a solvent in cosmetic, perfumes and paints which create a positive impact on society by making lives easier with these products being available for use.
However, ethanol is derived from petroleum involving the process of cracking and dehydration. The mining of petroleum is environmentally damaging as it can cause problems like contamination of soil, erosion and oil leaks. Moreover, ethanol is volatile and flammable thus explosion may occur when it comes into contact with heat or flames if it is not stored properly which pose a severe risk to society.
Weighing up the pros and cons, ethanol is not good to be used as solvents as it poses a great risk to society due to its flammability which outweighs its positive impact of making lives easier.
Hey Katherine!
Ok so let's start off breaking down the question and analysing the mark distribution:
Straight away, 2 marks for providing two equations for the two uses. (However, if your content isnt satisfactory, teacher may only award one mark for the equations because the equations are meant to be there to support your explanations. If your explanation isnt too desirable, it deprives the meaning of having an equation included).
1 mark for assessing (i.e. making a judgment)
2 marks for identifying the use of ethanol and explaining its impact on
society (you may not be awarded any mark for just simply identifying the use, nor would you be awarded any mark for explaining impacts upon
environment, but something you can relate to is that CO2 continuously contribute to greenhouse effect, and this will making the Earth environment inhospitable for human society.)
2 marks for identifying a second use of ethanol and explaining its impact on society.
What I do like about your response, is your frequent use of cause and effect language and your ability to make several judgments. These are evidences of you clearly understanding how to answer an explain/assess question! Well done! You have also included several social impacts and have also explained why these impacts are positive/negative. Another positive aspect of your response is the fact that you have provided the chemistry principles behind these uses, such as your successful identification of the -OH hydroxyl group and the hydrocarbon group. This answers the part "using underlying chemistry".
A fatal error (please dont be scared off by this harsh tone
its still an articulate response!) in your writing is that you are
overly focusing on environmental impacts. This is a question asking about
social impacts, as soon as you mention the word environment, you are off-topic. If this question is on "society and environmental impacts", I would give 7/7 for your response, beyond all doubts. Even if you want to include environmental impacts, you will still need to ultimately relate it back to effect upon society, just like what you have done with the global warming concept. When you talked about arable land, I thought you would follow up with the idea "the use of land and agricultural products for the production of ethanol would create competition with human consumption" (this is a good idea for
social impact if you wanna put it in). But instead you made a great point on
environmental impact, but again it's not relevant to the question.
A small technicality error is your chemical formula for ethanol. You wrote
C2H6O, but the more correct way of expressing it is
C2H5OH. Sure, these two formulae have exactly the same number of hydrogen atoms, but we must not ignore the significance of the
-OH hydroxyl group in ethanol, because that is what allows ethanol to dissolve in water! By writing C
2H
6O, you are ignoring the significance of -OH and it leaves a chance for the teacher to deduct you a mark there!
Overall, I would personally give a 5/7. Your teacher may give a 4-5/7. So essentially your response is a brand 5 range response, which is definitely good at this stage. If you apply my feedbacks, this would definitely be a band 6 response!
Well done overall!
Best Regards
Happy Physics Land