The way students address the keywords of the question, Justify and Evaluate, will distinguish them as aband 6 student.
Justifying involves providing evidence for a particular statement conclusion, and quantifying that.
Evaluating, requires you to present certain criteria and then make some sort of qualitative judgement based on these criteria.
I just found my Chem half-yearly exam paper, and there was a 6 marker based on ethanol. The question was 'Assess the role of the process of fermentation in reducing our consumption of fossil fuels'. here's the answer i wrote:
As fossil fuels continue to become more and more scarce, research and development should be invested into the production of biofuels through processes of fermentation of biomass. Cellulose is a key component of biomass, which can be broken down into glucose monomers by the acid hydrolysis of cellulose:
H+
C6H10O5(aq) + (n-1)H20(l) ----> C6H12O6 (aq)
Cellulose can also be broken down by the cellulase enzyme found in the stomachs of ruminants. Glucose obtained can then undergo fermentation by a yest complex known as zymase, to produce an ethanol solution:
zymase
C6H12O6 (aq) ---------> 2CH3CH2OH(aq) + 2CO2(g)
Cellulose used for the fermentation of glucose can be obtained from waste material of sugar cane and other waste plant material. Another interesting development is the use of Xylose (C5H10O5), another monosaccharide which can be fermented by the yeast Saccharomyces Cereviseae. This is a more efficient process than using Cellulose, as acid hydrolysis of cellulose is an expensive, polluting process, hence is NOT economically viable, while directly using Xylose in fermentation, using saccharomyces cereviseae, to produce Ethanol, is a far more efficient, economically viable process. This is because Xylose is obtained directly from the waste by-products of sugar-cane processing. The fermentation of glucose or xylose, produces ethanol, which ultimately is a renewable resource, as biomass is also renewable, producing many billions of tonnes of monosaccharides such as glucose through photosynthesis.
Society's consumption of fossil fuels is concentrated in the use of petroleum to obtain petrol. Pure Ethanol can be obtained from an aqueous ethanol solution produced by fermentation, by passing the solution through a zeolite Aluminium Silicate filter, which removes the water molecules, leaving a pure ethanol solution that can be used as petrol for cars. However, production of EThanol is still not economically viable, as the technology used to produce Ethanol is yet to be subsidised or commercialised, and modifications of car systems would be required. Hence, this makes Ethanol production an unpopular choice. However, as fossil fuel resources continue to dwindle, countries will need to invest in the research and development of Ethanol by fermentation, in order to ease the burden on fossil fuel resources which are rampantly consumed.
YESSS ITS VERYY LONG lol for a 6 marker
But there was a whole a4 page of lines left for writing space and I wrote really tiny.
Now I've enhanced my ethanol responses in explaining how ethanol is used in obtaining raw materials for producing plastics (polyethylene).
. Thanks in advance.