VCE Chemistry Question Thread

[HasibA]

For the Zwitterion structure of the amino acid aspartic acid, would you only deprotonate one of the carboxy groups? If so which one?

pretty sure just one, as you just have to show that 'a' COOH func. group protonates , and another func group accepts , for the COO- to act as the base and the other func group to act as a acid- not too sure tho, pretty sure you can pick either COOH group to show it protonates

if that makes sense- extra question: if both carboxylic acids protonate, what happens then? still classified as a Zwitterion right, but is there a diff. name for it now?

i hope this helps sorry if it doesn't make much sense

[jazzaa36]

Hello, tomorrow i have a summary epi sac on three epi's i did: gravimetric, Uv spec and Redox titration. My teacher was very vague of explaining what even potentially could be on the summary sac (p.s its only out of 10marks)
So could care to explain to me what kind of questions i could be expecting etc? Im so lost atm 

[@#035;3]

Do we have to know about thermal cracking? If so, can someone give me a run down of everything we need to know about it?
Cheers.

[Sine]

Do we have to know about thermal cracking? If so, can someone give me a run down of everything we need to know about it?
Cheers.

It really isn't on the course but you may see a few questions from really old exams or your school may teach it.

Cracking is just taking an alkane and using heat or a catalyst to convert it to a shorter alkane and alkene.
The products cannot be determined as a single alkane can "crack" multiple ways.

e.g C8H18--->C3H6 + C5H12
 or C8H18---->C5H10 + C3H8

[Rumena]

Hey guys, i have a chemistry sac tomorrow and it's our 2nd sac for unit 3, however my teacher did not tell us what topic it would be on, now I'm so stressed because i don't know what to study for. What did u guys do for ur 2nd sac?

[Sine]

Hey guys, i have a chemistry sac tomorrow and it's our 2nd sac for unit 3, however my teacher did not tell us what topic it would be on, now I'm so stressed because i don't know what to study for. What did u guys do for ur 2nd sac?

usually the second sac is on producing aspirin or preparation of an ester (chemical pathways). Have you done a experiment for this sac?

[Rumena]

No we haven't because we are doing the experiment and the write up tomorrow.
We haven't started on aspirin yet because that's 4 chapters away, however we have done chemical pathways but only 2 chapters of it, do you think it would be on those 2 chapters?

[Sine]

No we haven't because we are doing the experiment and the write up tomorrow.
We haven't started on aspirin yet because that's 4 chapters away, however we have done chemical pathways but only 2 chapters of it, do you think it would be on those 2 chapters?

I think there is only 2 chapters on chemical pathways. Chapters 9 & 10 in the heinemann book?

If it is a chemical pathway sac learn how to form an ester from alkanes/alkenes in doing so you learn most of the organic chemical reactions in vce.

[JellyBeanz]

No we haven't because we are doing the experiment and the write up tomorrow.
We haven't started on aspirin yet because that's 4 chapters away, however we have done chemical pathways but only 2 chapters of it, do you think it would be on those 2 chapters?

Some schools do the Aspirin SAC before the actual chapter completion because it's essentially chemical pathways. However, your SAC may very well be on other things related to chemical pathways, for example the synthesis of esters from carboxylic acids and alcohols.

[Rumena]

I think there is only 2 chapters on chemical pathways. Chapters 9 & 10 in the heinemann book?

If it is a chemical pathway sac learn how to form an ester from alkanes/alkenes in doing so you learn most of the organic chemical reactions in vce.

That is so true haha i just checked! I think it might be on those two chapters then, because she told us it's on a recent chapter that we've done. Thankyou so much

[Rumena]

Some schools do the Aspirin SAC before the actual chapter completion because it's essentially chemical pathways. However, your SAC may very well be on other things related to chemical pathways, for example the synthesis of esters from carboxylic acids and alcohols.

Yeah that's true, but she said we did the chapters already therefore it's probably on what you said about the synthesis of esters and all. Thanks!

[Elizawei]

Just wondering, is Fractional distillation still on the 3/4 course?

[ccdes0001]

Can someone please explain why (c) is the answer...

0.132 g of a pure carboxylic acid (R–COOH) was dissolved in 25.00 mL of water and titrated with
0.120 M NaOH solution. A volume of 14.80 mL was required to reach the endpoint of the titration.

Question 9
Which of the following best represents the pH of the solution at the equivalence point and the name of a suitable
indicator for this titration?
 pH at the equivalence point suitable indicator
A. less than 7 phenolphthalein
B. less than 7 bromophenol blue
C. greater than 7 phenolphthalein
D. greater than 7 bromophenol blue

[plants]

Just wondering, is Fractional distillation still on the 3/4 course?

Nope -  was removed when the 2013-2016 study design came to implementation

[Elizawei]

Nope -  was removed when the 2013-2016 study design came to implementation

Thanks!