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March 28, 2024, 08:15:42 pm

Author Topic: VCE Chemistry Question Thread  (Read 2312987 times)  Share 

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gnaf

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Re: VCE Chemistry Question Thread
« Reply #6540 on: September 06, 2017, 12:42:56 pm »
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In the first pic, how do you do 4b)? I keep on getting  53% as the answer but the answer us actually 5.92%!

I did %m/m= m(C2H2O4)/m(soln= NaOH+ C2H2O4)=(0.01315*90)*100/(1.1835+0.026*90)=53%

In the 2nd pic, I got C=0.2209 but the answer is 0.201M. I got V(MnO4-)=0.01313, so n(MnO4-)=0.0017675. So n(CH3OH)=(5/4)*n(MnO4-)=0.002. So C(CH3OH)= 0.2209, not 0.201
« Last Edit: September 06, 2017, 01:20:13 pm by gnaf »

gnaf

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Re: VCE Chemistry Question Thread
« Reply #6541 on: September 06, 2017, 01:21:53 pm »
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Hi again- How do you do 5a)?

I got 0.674 mol/L but the ans is 6.74mol/L

Just tryna scrape a pass for volumetric, thanks!! :-[

Edit: Another question! How do you do 15b)?
I did this:
n(MnO4-)=0.00416
n(alcohol)=(5/4)*n(MnO4-)=0.0052
C(alcohol)=0.0052/0.02=0.26
0.26*M=14.00
M=53.84
But the ans is M=59.98 mol/ L
« Last Edit: September 06, 2017, 03:03:43 pm by gnaf »

Natasha.97

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Re: VCE Chemistry Question Thread
« Reply #6542 on: September 06, 2017, 01:30:02 pm »
+5
In the first pic, how do you do 4b)? I keep on getting  53% as the answer but the answer us actually 5.92%!

I did %m/m= m(C2H2O4)/m(soln= NaOH+ C2H2O4)=(0.01315*90)*100/(1.1835+0.026*90)=53%

In the 2nd pic, I got C=0.2209 but the answer is 0.201M. I got V(MnO4-)=0.01313, so n(MnO4-)=0.0017675. So n(CH3OH)=(5/4)*n(MnO4-)=0.002. So C(CH3OH)= 0.2209, not 0.201

Hi!

I did the second question and got 0.2209 as well :)
Life is weird and crazy as heck but what can you do?

gnaf

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Re: VCE Chemistry Question Thread
« Reply #6543 on: September 06, 2017, 02:17:01 pm »
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Thanks heaps Jess :D

If you or anyone else could do the 1st or 3rd question too, that'd be great!

Thanks again :)

Natasha.97

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Re: VCE Chemistry Question Thread
« Reply #6544 on: September 06, 2017, 03:19:33 pm »
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Hi again- How do you do 5a)?

I got 0.674 mol/L but the ans is 6.74mol/L

Just tryna scrape a pass for volumetric, thanks!! :-[

Hi!

Not 100% sure if this is correct, but here is my working out:



Hope this helps
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-273.15

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Re: VCE Chemistry Question Thread
« Reply #6545 on: September 09, 2017, 10:37:47 am »
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hello!
Im a bit confused
In the formation of a peptide, is the peptide / amide link / bond just the individual bond between the N-C or is it considered the whole CONH group??
Because im finding that some resources will circle the whole group and label it as the peptide link but others will just point to the N-C bond

Thanks for your help :)

Willba99

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Re: VCE Chemistry Question Thread
« Reply #6546 on: September 09, 2017, 11:07:05 am »
+2
hello!
Im a bit confused
In the formation of a peptide, is the peptide / amide link / bond just the individual bond between the N-C or is it considered the whole CONH group??
Because im finding that some resources will circle the whole group and label it as the peptide link but others will just point to the N-C bond

Thanks for your help :)

I think both responses would be acceptable! Personally, I would just circle the N-C bond, but they would probably accept if you circled the whole CONH
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VanillaRice

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Re: VCE Chemistry Question Thread
« Reply #6547 on: September 09, 2017, 12:26:54 pm »
+5
hello!
Im a bit confused
In the formation of a peptide, is the peptide / amide link / bond just the individual bond between the N-C or is it considered the whole CONH group??
Because im finding that some resources will circle the whole group and label it as the peptide link but others will just point to the N-C bond

Thanks for your help :)
I think writing it as the -CO-NH- group is a safer bet. C-N is not necessarily restricted to amides - consider for example, amines, which also have a C-N bond.
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sweetiepi

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Re: VCE Chemistry Question Thread
« Reply #6548 on: September 09, 2017, 02:29:11 pm »
+7
hello!
Im a bit confused
In the formation of a peptide, is the peptide / amide link / bond just the individual bond between the N-C or is it considered the whole CONH group??
Because im finding that some resources will circle the whole group and label it as the peptide link but others will just point to the N-C bond

Thanks for your help :)
I'm with VanillaRice, I'd definitely circle the CONH, just to be sure. :)
C-N is a bit general imo, whereas the CONH group is specifically grouped as an amide. :)
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Sine

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Re: VCE Chemistry Question Thread
« Reply #6549 on: September 09, 2017, 03:02:53 pm »
+4
hello!
Im a bit confused
In the formation of a peptide, is the peptide / amide link / bond just the individual bond between the N-C or is it considered the whole CONH group??
Because im finding that some resources will circle the whole group and label it as the peptide link but others will just point to the N-C bond

Thanks for your help :)
definitely agree with VanillaRice and insanpi, circle the CONH :)

gemmaruffin

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Re: VCE Chemistry Question Thread
« Reply #6550 on: September 09, 2017, 05:49:35 pm »
+1
I'm with VanillaRice, I'd definitely circle the CONH, just to be sure. :)
C-N is a bit general imo, whereas the CONH group is specifically grouped as an amide. :)

Agreed, because in a sample test I did I just circled the C-N and got it marked wrong (my teacher marks exams) so would recommend doing them all :)
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Willba99

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Re: VCE Chemistry Question Thread
« Reply #6551 on: September 09, 2017, 06:07:57 pm »
+2
Agreed, because in a sample test I did I just circled the C-N and got it marked wrong (my teacher marks exams) so would recommend doing them all :)

lollll well you learn something every day
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VanillaRice

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Re: VCE Chemistry Question Thread
« Reply #6552 on: September 09, 2017, 06:52:40 pm »
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Agreed, because in a sample test I did I just circled the C-N and got it marked wrong (my teacher marks exams) so would recommend doing them all :)
I think some of the confusion might be from the fact it can be referred to as a peptide 'bond', which implies a single bond. But, it can also be referred to as a functional group (peptide/amide group) or linkage, which in my opinion is less confusing.
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peanut

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Re: VCE Chemistry Question Thread
« Reply #6553 on: September 12, 2017, 08:57:28 pm »
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Is an ether link -C-O-C- or -O-? If asked to circle the ether link, would the red or green be sufficient (not sure whether to circle the carbons or not)?

Sine

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Re: VCE Chemistry Question Thread
« Reply #6554 on: September 12, 2017, 09:00:26 pm »
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Is an ether link -C-O-C- or -O-? If asked to circle the ether link, would the red or green be sufficient (not sure whether to circle the carbons or not)?
ether linkage is

R-O-R'

so don't include the carbons since it really can be anything