General Thoughts: Chemistry (1 Viewer)

[dan964]

uh im looking at 85+ conservatively, i think i got 90+ tho prob 85-90.
Uhm yeah my friend wrote about ethanol used in esterification. I think mostly people wrote about solvent and fuel cause it has the most chemistry behind it. I explained why etOH is an effective industry solvent and why ethanol was a fuel that could undergo combustion, also put an equation. Showed all the positives and negatives and overall said despite its costly production and its generally inefficiency in comparisson to octane fuel, its extensive use in all these industrial processes make it good. something like that. im banking on at least 5/7 hopefully.

Similar, because I felt like it I also briefly mentioned its production esp. fermentation and tied it into being a renewable resource.

 

[Swopneelfly]

Nope. U use it in alcoholic beverages but that is not in syllabus. And not much to write about that anyway. And if yoi wanted to go further you could've written aboit use in cosmetics.[emoji38]

But you can write about how alcohol use can cause diseases and violence and shit can't you?

 

[bhatman]

But you can write about how alcohol use can cause diseases and violence and shit can't you?

None of that is really chemistry based, and is not in the syllabus at all. It would be very hard to get those marks if you've argued about ethanol as a beverage, you'd damn near have to have a state rank quality response when talking about it and be convincing as hell to get all the allocated marks for it. You wouldn't be able to talk about the underlying chemical principles either, which was specified in the question.

 

[someth1ng]

None of that is really chemistry based, and is not in the syllabus at all. It would be very hard to get those marks if you've argued about ethanol as a beverage, you'd damn near have to have a state rank quality response when talking about it and be convincing as hell to get all the allocated marks for it. You wouldn't be able to talk about the underlying chemical principles either, which was specified in the question.

True, I'd love to see someone talk about oxidation of ethanol in the body to acetaldehyde and acetic acid. Would be great.

 

[mysterymarkplz]

Do you guys rekon the mark required for b6 for chem and its alligning for hsc marks will be better than last year? I think this year was harder than last year but not by that much.

 

[iStudent]

uh im looking at 85+ conservatively, i think i got 90+ tho prob 85-90.
Uhm yeah my friend wrote about ethanol used in esterification. I think mostly people wrote about solvent and fuel cause it has the most chemistry behind it. I explained why etOH is an effective industry solvent and why ethanol was a fuel that could undergo combustion, also put an equation. Showed all the positives and negatives and overall said despite its costly production and its generally inefficiency in comparisson to octane fuel, its extensive use in all these industrial processes make it good. something like that. im banking on at least 5/7 hopefully.

How do you guess your chem mark? Is that even possible considering you could lose literally half your marks for one tiny mistake (e.g. having dodgy limitations for that question I posted earlier) lol

Also @ aarondapho My teacher is actually a hsc marker but me being me I already went through 30 trial papers so I've pretty much have seen most questions along with their sample answers. (and hence wrote pretty good responses). Hsc questions are a bit more difficult because most questions you wouldn't have seen before :/ (and so marking guidelines could go all over the place).

 

[IR]

Do you guys rekon the mark required for b6 for chem and its alligning for hsc marks will be better than last year? I think this year was harder than last year but not by that much.

Na. It will be a higher cutoff

 

[iStudent]

How do you write chemical equations for ethanol as a solvent?
The question asked for equationssssss. At close to the last minute I realised this and I wrote in incomplete combustion of octane as my 2nd equation (in addition to my ethanol combustion one) to compare ethanol burning completely vs petrol burning incompletely. :/
What 2 equations did you guys have?

 

[photastic]

How do you write chemical equations for ethanol as a solvent?
The question asked for equationssssss. At close to the last minute I realised this and I wrote in incomplete combustion of octane as my 2nd equation (in addition to my ethanol combustion one) to compare ethanol burning completely vs petrol burning incompletely. :/
What 2 equations did you guys have?

Fermentation, photosynthesis, combustion.

 

[superstar12]

Anyone have a scanned copy of the paper?

 

[mysterymarkplz]

I took off 1-2 marks for almost every long response depending on how i felt with my answer. All my 2 markers were correct, i went around asking the top 5 how they went and most of them got the same answer as me. Also did the same thing for industrial. Ofc you can never be sure, the 20/20 for MC also helped out in that.

 

[bhatman]

IMO cut-off for band 6 will be around 78-79. Higher than last year, but not 80 because that would see too dramatic an increase from last year. However, I wouldn't really be surprised if it is 80 because the exam was quite straightforward in comparison to previous HSC exams.

 

[Ncm]

How do you write chemical equations for ethanol as a solvent?
The question asked for equationssssss. At close to the last minute I realised this and I wrote in incomplete combustion of octane as my 2nd equation (in addition to my ethanol combustion one) to compare ethanol burning completely vs petrol burning incompletely. :/
What 2 equations did you guys have?

draw a diagram?

 

[someth1ng]

All HSC chemistry exams are straightforward. The cut-off will probably continue hovering at ~75.

 

[SuchSmallHands]

uhh guys what do you mean ethanol---> ethylene is not valid?

I think its a perfectly justifiable use of ethanol...

Yeah that's totally valid.

 

[bhatman]

uhh guys what do you mean ethanol---> ethylene is not valid?

I think its a perfectly justifiable use of ethanol...

not really... we use ethene to produce ethanol in many instances as seen in the hydration of ethene to produce ethanol, and ethene is much more easily derived from the petrochemical industry. It isn't really a valid point to talk about its use as polymers and stuff because ethanol isn't used for that, and in itself using ethanol to create ethene doesn't really have much chemistry to it. If you're talking about ethanol's USE to produce ethene, then all you can really talk about is the dehydration reaction and little more; everything after that is related to the use of ethene, and even then can be much more easily derived from other avenues such as the cracking of long chained alkanes.
The best two uses of ethanol to have had IMO were its use as a fuel and as a universal solvent.

 

[SuchSmallHands]

not really... we use ethene to produce ethanol in many instances as seen in the hydration of ethene to produce ethanol, and ethene is much more easily derived from the petrochemical industry. It isn't really a valid point to talk about its use as polymers and stuff because ethanol isn't used for that, and in itself using ethanol to create ethene doesn't really have much chemistry to it. If you're talking about ethanol's USE to produce ethene, then all you can really talk about is the dehydration reaction and little more; everything after that is related to the use of ethene, and even then can be much more easily derived from other avenues such as the cracking of long chained alkanes.
The best two uses of ethanol to have had IMO were its use as a fuel and as a universal solvent.

Dehydration of ethanol to Ethene and then polymerisation/alkylation/halogenation is a totally valid use of ethanol. Anyone who wrote that is going to read what you just said and stress because they think they've made a mistake. More people probably went with solvent/fuel (I know it's what I thought of right away so I wrote about it) but ethanol as a renewable source of polymers currently derived from the petrochemical industry is completely fine.

 

[faisalabdul16]

not really... we use ethene to produce ethanol in many instances as seen in the hydration of ethene to produce ethanol, and ethene is much more easily derived from the petrochemical industry. It isn't really a valid point to talk about its use as polymers and stuff because ethanol isn't used for that, and in itself using ethanol to create ethene doesn't really have much chemistry to it. If you're talking about ethanol's USE to produce ethene, then all you can really talk about is the dehydration reaction and little more; everything after that is related to the use of ethene, and even then can be much more easily derived from other avenues such as the cracking of long chained alkanes.
The best two uses of ethanol to have had IMO were its use as a fuel and as a universal solvent.

When petroleum industry dies, how are you going to get ethylene? Using ethanol.

 

[bhatman]

Dehydration of ethanol to Ethene and then polymerisation/alkylation/halogenation is a totally valid use of ethanol. Anyone who wrote that is going to read what you just said and stress because they think they've made a mistake. More people probably went with solvent/fuel (I know it's what I thought of right away so I wrote about it) but ethanol as a renewable source of polymers currently derived from the petrochemical industry is completely fine.

Hmm I guess it has its merits in the renewable/sustainability sense, but even then I find it questionable because of the ease of the other processes

 

[mysterymarkplz]

Ethanol is primarily derived from fermentation because it is renewable. Ethanol derived from ethene is not renewable. The point is you would rather go with acid hydrolysis of sucrose -> glucose then fermentation as opposed to thermal/catalytic cracking of octane -> addition reaction with H2O under H2SO4. Idk if they'll mark you down for using ethene as a source, but although its possible, i've heard from teachers that its not realistic, and for most long responses, they want you to have a clear understanding of why ethanol is so good, and one of the biggest advantages is that it is renewable.