Login

Search the forums now!

Welcome, Guest. Please login or register.

June 17, 2025, 03:19:20 pm
Pages: 1 [2] 3 4 5   Go Down

Author Topic: STAV 2010  (Read 8045 times)  Share 

0 Members and 1 Guest are viewing this topic.

Studyinghard

  • Victorian
  • Part of the furniture
  • *****
  • Posts: 1313
  • Respect: +4
Re: STAV 2010
« Reply #15 on: May 28, 2010, 06:27:02 pm »
0
84% for this one. Average.?
Logged
"Your life is like a river, no matter what you just got to keep on going"

Mao

  • CH41RMN
  • Honorary Moderator
  • Great Wonder of ATAR Notes
  • *******
  • Posts: 9181
  • Respect: +390
  • School: Kambrya College
  • School Grad Year: 2008
Re: STAV 2010
« Reply #16 on: May 29, 2010, 02:24:53 am »
0
Quote from: Greggler on May 28, 2010, 04:51:09 pm
However for those that were wandering a multiplet is something like >5 splits in the peak.

Nope. Sextets, Septets, Octets are not classified as multiplets, these are very well defined and commonplace for organic chemistry.

A multiplet generally refer to peaks that are a mess, where a range of things can happen, such as overlapping of different environments, or crazy multiplicity. These makes the splitting pattern impossible to determine, so we throw it in the too hard basket.

The ester in question is propyl methanoate. The second H environment in the propyl is split by a CH3 group and a CH2O group. These two groups are very different, multiplicity dictates there will be a triplet of quartets. Since the environments are fairly different, nice overlapping does not occur, and you end up with literally, a mess. It is impossible to identify from this mess that it is a triplet of quartets, therefore it is classified as a 'multiplet'.

For more info, see http://vcenotes.com/forum/index.php/topic,26044.msg263934.html#new
Logged
Editor for ATARNotes Chemistry study guides.

VCE 2008 | Monash BSc (Chem., Appl. Math.) 2009-2011 | UoM BScHon (Chem.) 2012 | UoM PhD (Chem.) 2013-2015

kyzoo

  • Victorian
  • ATAR Notes Superstar
  • ******
  • Posts: 2040
  • Respect: +23
Re: STAV 2010
« Reply #17 on: May 29, 2010, 04:46:29 pm »
0
I just did this exam and i have some queries with it

---

1. Draw the semistructural formula for all esters with the molecular formula C4H8O2.

The solutions say that there are 3 possible esters, HCOOCH2CH2CH3, CH3COOCH2CH3, CH3CH2COOHCH3

However there are actually 4 possible esters

There is also 2-propyl methanoate HCOOCH(CH3)2

---

Attached Picture

NaOH absorbs atmospheric CO2 to become NaCO3. However, don't both NaOH and NaCO3 react with HCl? Hence if regardless of how much time has passed and how much NaOH has been converted to NaCO3, the titre of HCl should still be the same?
« Last Edit: May 29, 2010, 04:49:12 pm by kyzoo »
Logged
2009
~ Methods (Non-CAS) [48 --> 49.4]

2010
~ Spesh [50 --> 51.6]
~ Physics [50 --> 50]
~ Chem [43 --> 46.5]
~ English [46 --> 46.2]
~ UMEP Maths [5.0]

2010 ATAR: 99.90
Aggregate 206.8

NOTE: PLEASE CONTACT ME ON EMAIL - [email protected] if you are looking for a swift reply.

iffets12345

  • Victorian
  • Part of the furniture
  • *****
  • Posts: 1414
  • Respect: +15
Re: STAV 2010
« Reply #18 on: May 29, 2010, 04:53:00 pm »
0
Taking a guess, isn't it Na2CO3? Being a carbonate means it requires 2 hydrogens in the reaction, unlike hydroxide which is a one to one ratio. Hence, you would need a larger titre for the carbonate ion.
Logged
Feel free to message on dentistry questions

kyzoo

  • Victorian
  • ATAR Notes Superstar
  • ******
  • Posts: 2040
  • Respect: +23
Re: STAV 2010
« Reply #19 on: May 29, 2010, 04:54:59 pm »
0
Quote from: iffets12345 on May 29, 2010, 04:53:00 pm
Taking a guess, isn't it Na2CO3? Being a carbonate means it requires 2 hydrogens in the reaction, unlike hydroxide which is a one to one ratio. Hence, you would need a larger titre for the carbonate ion.

I guess, but if that's true then you need an even bigger titre of HCl to reach equivalence point.
Logged
2009
~ Methods (Non-CAS) [48 --> 49.4]

2010
~ Spesh [50 --> 51.6]
~ Physics [50 --> 50]
~ Chem [43 --> 46.5]
~ English [46 --> 46.2]
~ UMEP Maths [5.0]

2010 ATAR: 99.90
Aggregate 206.8

NOTE: PLEASE CONTACT ME ON EMAIL - [email protected] if you are looking for a swift reply.

iffets12345

  • Victorian
  • Part of the furniture
  • *****
  • Posts: 1414
  • Respect: +15
Re: STAV 2010
« Reply #20 on: May 29, 2010, 04:56:05 pm »
0
yup isnt that what the question said?
Logged
Feel free to message on dentistry questions

kyzoo

  • Victorian
  • ATAR Notes Superstar
  • ******
  • Posts: 2040
  • Respect: +23
Re: STAV 2010
« Reply #21 on: May 29, 2010, 04:57:06 pm »
0
Accoridng to the question, the fresh NaOH in which none of it has become Na2CO3 requires a bigger titre of HCl than the stale NaOH
Logged
2009
~ Methods (Non-CAS) [48 --> 49.4]

2010
~ Spesh [50 --> 51.6]
~ Physics [50 --> 50]
~ Chem [43 --> 46.5]
~ English [46 --> 46.2]
~ UMEP Maths [5.0]

2010 ATAR: 99.90
Aggregate 206.8

NOTE: PLEASE CONTACT ME ON EMAIL - [email protected] if you are looking for a swift reply.

iffets12345

  • Victorian
  • Part of the furniture
  • *****
  • Posts: 1414
  • Respect: +15
Re: STAV 2010
« Reply #22 on: May 29, 2010, 05:04:37 pm »
0
oh! my bad. Yea, then ur right><
Logged
Feel free to message on dentistry questions

kakar0t

  • Victorian
  • Forum Obsessive
  • ***
  • Posts: 310
  • Respect: +1
Re: STAV 2010
« Reply #23 on: May 29, 2010, 10:09:48 pm »
0
you call this an exam? hahahaha
Logged

Studyinghard

  • Victorian
  • Part of the furniture
  • *****
  • Posts: 1313
  • Respect: +4
Re: STAV 2010
« Reply #24 on: May 29, 2010, 10:24:24 pm »
0
Quote from: kakar0t on May 29, 2010, 10:09:48 pm
you call this an exam? hahahaha

wow cocky much?
Logged
"Your life is like a river, no matter what you just got to keep on going"

kakar0t

  • Victorian
  • Forum Obsessive
  • ***
  • Posts: 310
  • Respect: +1
Re: STAV 2010
« Reply #25 on: May 29, 2010, 11:55:17 pm »
0
Quote from: Studyinghard on May 29, 2010, 10:24:24 pm
Quote from: kakar0t on May 29, 2010, 10:09:48 pm
you call this an exam? hahahaha

wow cocky much?

haha im kiddin mate ;) i wish i could be cocky at this point in time before the exams >.>
Logged

stonecold

  • Victorian
  • Great Wonder of ATAR Notes
  • *******
  • Posts: 5335
  • Respect: +255
  • School Grad Year: 2010
Re: STAV 2010
« Reply #26 on: May 30, 2010, 07:32:05 pm »
0
Am I going stuuupid, or to quote Martoman, is STAV on crack :P.
Firstly
Q 9di.  it says name bonding types, other than covelent, which give this protein its structure.
Then in the answers it said you needed di-sulfide.  Di sulfide is a covelent BOND!
And also, the covelent bond between the sulfur molecules isn't even present.  You have to draw it in yourself in the next question!

Q 7d.  If the theoretical mass is 0.273, and the actual mass is 0.268, then doesn't that make the percentage yield lower than 100, or am I just going crazy?
« Last Edit: May 30, 2010, 07:33:38 pm by stonecold »
Logged
2011-13: BBiomed (Microbiology & Immunology Major) @ UniMelb


VCE 2009'10: English 46 | English Language 49 | Chemistry 50 | Biology 50 | Further Mathematics 48 | Mathematical Methods CAS 39
ATAR: 99.85

"Failure is not when one falls down but rather when one fails to get up" - unknown

cipherpol

  • Victorian
  • Forum Obsessive
  • ***
  • Posts: 282
  • Respect: +3
Re: STAV 2010
« Reply #27 on: May 30, 2010, 07:34:45 pm »
0
Quote from: stonecold on May 30, 2010, 07:32:05 pm
Q 7d.  If the theoretical mass is 0.273, and the actual mass is 0.268, then doesn't that make the percentage yield lower than 100, or am I just going crazy?

lol, yeh, i was like wtf when i saw the answers.
Logged
2009: Biology
2010: Eng Lang, Chem, Physics, Methods, Spesh

stonecold

  • Victorian
  • Great Wonder of ATAR Notes
  • *******
  • Posts: 5335
  • Respect: +255
  • School Grad Year: 2010
Re: STAV 2010
« Reply #28 on: May 30, 2010, 07:39:32 pm »
0
Well in that case, and considering wikipedia never lies (http://en.wikipedia.org/wiki/Disulfide_bond), then I got 94%. :)

God I hope I can pull something like this on the exam...
Logged
2011-13: BBiomed (Microbiology & Immunology Major) @ UniMelb


VCE 2009'10: English 46 | English Language 49 | Chemistry 50 | Biology 50 | Further Mathematics 48 | Mathematical Methods CAS 39
ATAR: 99.85

"Failure is not when one falls down but rather when one fails to get up" - unknown

cameron_15

  • Victorian
  • Forum Obsessive
  • ***
  • Posts: 258
  • Respect: +1
Re: STAV 2010
« Reply #29 on: May 30, 2010, 07:40:13 pm »
0
%102...

good, i guess...

Haha
Logged
VCE: Biology 42 (43.23)|Chemistry 42 (45.88)|English 43 (42.87)|Physics 45 (47.07)| Maths methods 40 (45.14)|Specialist maths 34 (41.70)

ATAR: 98.65

2011:
Pages: 1 [2] 3 4 5   Go Up