VCE Chemistry Question Thread

[Freddie Hg]

DO we need to know how to do combustion analysis? Do you guys thing it's going to be in the exam?

whats that? mind providing a study design point, question or page of a book?

[zenith101]

anyone have VCAA accepted definitions/can explain generally what is precision, accuracy, reliability and validity, and how to generally improve all 4 measures. Thank you very much.

[ilikenoodlez]

do we lose marks each time we don't round to the correct no. of sig figs or use the wrong state when writing chemical equations?

[Freddie Hg]

do we lose marks each time we don't round to the correct no. of sig figs or use the wrong state when writing chemical equations?

i believe theres on designated question each year which has a mark allocated for sig figs. however this question is unkown so best to round everything to the lowest sig figs.
and yes you do lose marks for wrong state

[MAGGOT]

In the VCAA 2010 exam 2 question 14. My thought process was that A and D are definitely wrong so only B and C remained. From that i didn't know which answer was right or wrong so why is C wrong and B right.
Thanks.

[sweetcheeks]

In the VCAA 2010 exam 2 question 14. My thought process was that A and D are definitely wrong so only B and C remained. From that i didn't know which answer was right or wrong so why is C wrong and B right.
Thanks.

C talks about 1 mole of gaseous ethanol but the equation specifies that the ethanol is in a liquid state.

[minhalgill]

hydrogens are in the same environment if theyre bonded to the same carbon in the same way, right? how would we distinguish between carbon environments?

[Freddie Hg]

hydrogens are in the same environment if theyre bonded to the same carbon in the same way, right? how would we distinguish between carbon environments?

in almost the same fashion. example this molecule has 5 different carbon environments as the carbons are each bonded to different groups
whereas propanol only has 2 carbon environments and you can clearly see how the different carbon environments are bonded
idk its sorta intuitive after a-lot of practice

[minhalgill]

how many would you say this one attatched has?

whereas propanol only has 2 carbon environments and you can clearly see how the different carbon environments are bonded
idk its sorta intuitive after a-lot of practice

dont you mean 3 for propanol?

[Freddie Hg]

how many would you say this one has?

dont you mean 3 for propanol?

i did that on purpose to teach you carbon environments 
na my bad i was looking at a different pic. but you clearly understand carbon environments

how many would you say this one attatched has?

dont you mean 3 for propanol?

10? can you confirm if you have sols cause i really wanna know

MOD EDIT: merged posts

[minhalgill]

10? can you confirm if you have sols cause i really wanna know

lmao, its 8

[Freddie Hg]

lmao, its 8

damn i was gonna say that, but i still think its ten.
 other than the benzene ring it has 6 carbon enviroments in the benzene ring there are 6 carbons 2 of which are by default different since they connect to different parts of the chain (outermost two carbons) and the 4 inner carbons represent 2 carbon environments all together.
the inner 4 carbons should have 2 environments as 2 carbons are bonded to one of the different outermost carbons. 4 benzene carbon envs plus 6
my reasoning behind it being 8 was that the outermost and the inner carbons all represent 2 carbon env due to symmetry. however that cant be true since either side of the benzene ring is non symmetrical.  with this logic the other molecule i posted with 5 carbon environments is wrong
 can anyone else give it a shot

[Bri MT]

hydrogens are in the same environment if theyre bonded to the same carbon in the same way, right? how would we distinguish between carbon environments?

If you go on the free notes section of AN I uploaded HNMR notes that will probably help more with identifying environments than I can describe with words alone.

[Freddie Hg]

If you go on the free notes section of AN I uploaded HNMR notes that will probably help more with identifying environments than I can describe with words alone.

i think they are asking about CNMR. hey mini can you do the question that minhalgill sent. and can you explain the logic behind 8 carbon environments

[Bri MT]

i think they are asking about CNMR. hey mini can you do the question that minhalgill sent. and can you explain the logic behind 8 carbon environments

That was in response to the first question about hydrogen environments

Yeah,  I'll take a look and edit this post accordingly


The answer should be 10 - I even looked up the CNMR online and that showed 10