Chemistry Predictions/Thoughts (1 Viewer)

[Luukas.2]

doesnt 1,2-dichloroprop-1-ene fit cause you could assume Q might have a double bond and since doesnt specify excess cl2 it could only have 1 double bond being saturated also 1,2-dichloroprop-1-ene has 32 percent carbon by mass and has molecular ion peak at 114 it also has a fragment at 15 and 62?

No, it doesn't. 1,2-dichloroprop-1-ene could not be made by addition to an alkene.

Starting with propadiene (CH₂=C=CH₂) would yield 2,3-dichloroprop-1-ene assuming reaction with one equivalent (assuming that dienes like this react in this way), rather than to yield 1,2-dichloroprop-1-ene.

Starting with propyne (CH₃-CCH) would yield an addition product of 1,2-dichloroprop-1-ene from 1 equivalent, but the question specified that the starting material was an alkene, Q, so Q can't be propyne.

Further, if the product was 1,2-dichloroprop-1-ene, ClCH=CCl-CH₃, its parent ions would be:

• C₃H₄³⁵Cl₂^{+ .} at m/z = 3 x 12 + 4 + 35 x 2 = 110
• C₃H₄³⁵Cl₁³⁷Cl₁^{+ .} at m/z = 3 x 12 + 4 + 35 + 37 = 112
• C₃H₄³⁷Cl₂^{+ .} at m/z = 3 x 12 + 4 + 37 x 2 = 114

with relative intensities 9 : 6 : 1, yet the mass spectrum provided clearly shows the largest intensity molecular ion is at 112.

 

[Luukas.2]

there is literally no reason not to scan the entire page. scanning just the area with the lines surely is more tedious than just scanning the entire page. and it also has that like "dont write anything below this line" section, so i think that would make it explicit if they don't want you to write a bit outside of the lines

The "don't write in this area" section is where the booklets will be cut into individual sheets to feed into the scanner. This will be done by machine (take booklet, cut off margin and staple, feed sheet by sheet into scanner, produce image file of paper) so the scanned part will be as much of the page as is not cut off. No doubt some of the "don't write here" part does end up in the scans, but they do mean it that those parts may not be marked simply because no one will ever see them.

 

[carrotsss]

The "don't write in this area" section is where the booklets will be cut into individual sheets to feed into the scanner. This will be done by machine (take booklet, cut off margin and staple, feed sheet by sheet into scanner, produce image file of paper) so the scanned part will be as much of the page as is not cut off. No doubt some of the "don't write here" part does end up in the scans, but they do mean it that those parts may not be marked simply because no one will ever see them.

I don’t think they mean that part because it’s pretty explicit there, I think they mean the bit outside those corner things

 

[scaryshark09]

this question for example i wrote stuff in the blank white area which is fine. the entire page gets scanned. if you want proof, just look at sample student responses from previous years. it also just says don't write in the centre margin, and at the very bottom of the page, everything else is fine

 

[Retrodawn]

will I lose marks if I rounded my calculation of the ammonia back titration to 2sf instead of 4?

 

[swarley2345]

it depends on the marking criteria, for some questions they care about sig figs, for others they dont.

 

[kms1234]

Has there been no progress on getting the full paper. Everyday i dont see it, the more I die inside

 

[tywebb]

Has there been no progress on getting the full paper. Everyday i dont see it, the more I die inside

Here is another version with all the questions, but it is out of order

EDIT: see post #439 for reordered version

 

[Interdice]

Here is another version with all the questions, but it is out of order

Outta curiosity. Where did you get the paper the first time? Cool if you don't want to answer

 

[lolcti]

Outta curiosity. Where did you get the paper the first time? Cool if you don't want to answer

Interdice does chem?! I thought you just talked ab depressing shit all day

 

[Interdice]

Interdice does chem?! I thought you just talked ab depressing shit all day

The only thing bigger than my Asian fetish is my hate for Chemistry

 

[Interdice]

Also for Q16. The answer is the compound with the bigger ksp. Right?

 

[ghreysantomy]

Also for Q16. The answer is the compound with the bigger ksp. Right?

Q16 was (B)
=> AgI precipitates out first as it has a SMALLER Ksp and so less of it needs to be added into a given volume before it begins to precipitate, compared to AgCl, whose Ksp is larger. The solutions, by PEAK, were posted on this thread a few days ago.

 

[Interdice]

Q16 was (B)
=> AgI precipitates out first as it has a SMALLER Ksp and so less of it needs to be added into a given volume before it begins to precipitate, compared to AgCl, whose Ksp is larger. The solutions, by PEAK, were posted on this thread a few days ago.

Thanks

 

[tywebb]

Here is another version with all the questions, but it is out of order

Here is a better version with questions in proper order. It is also unredacted unlike nesa's version.

 

[tywebb]

now nesa put it up: https://educationstandards.nsw.edu....exam-papers/2023/chemistry-2023-hsc-exam-pack

albeit with q2, 16, 18 partially redacted

my version is better!

 

[sneak11]

if for the 9 mark spectroscopy question i had put carboxyl accidentally instead of carbonyl but put (ketone) in brackets, is there a possibility i might still get that mark?

 

[SadCeliac]

Here is a better version with questions in proper order. It is also unredacted unlike nesa's version.

THANKS TYWEBB

 

[Luukas.2]

if for the 9 mark spectroscopy question i had put carboxyl accidentally instead of carbonyl but put (ketone) in brackets, is there a possibility i might still get that mark?

If you've drawn a ketone, written ketone, and spoken of carbonyl (correctly) in the justification that accompanies the table, I think there is a far argument to be made that you should be credited despite a minor mistake. However, if you've made the same mistake in the justification or if your answer (overall) comes across as reflecting uncertainty or as being mistaken, being penalised is the fair outcome.

Having said that, if the marking scheme treats the table and structures specifically and separately, then you could be out of luck.

Note, also, that giving two answers is generally discouraged. Suppose someone wrote carbonyl (aldehyde) and then drew a ketone, for example... the functional group is correct but the additional (and unrequested) compound class is incorrect. Should that be ignored? What if the answer said "aldehyde (carbonyl)," so that the second answer is the correct one?

In your case, would you credit the answer ketone alone, without the proper name of a functional group provided? I would argue against that being credited, but an earlier question incorrectly portrayed aldehydes and ketones as having different functional groups, so taking a hard line on functional groups vs. compound classes seems harsh.

So... is there a possibility of you getting the mark? Yes. Is there a possibility of you doing anything to influence the decision now? None at all. My advice is: move on.

 

[tywebb]

matrix solutions: https://www.matrix.edu.au/2023-hsc-chemistry-exam-paper-solutions/