Rough Solutions for Exam

[illuminati]

For 4d,
you could say that if you run the sample through mass spec, you can find its molecular mass, and compare that with propyl proponaotes molecular mass,
Right?

that's what i said

For 4d,
you could say that if you run the sample through mass spec, you can find its molecular mass, and compare that with propyl proponaotes molecular mass,
Right?

that's what i said

this reasoning is wrong because your impure propyl propanoate sample would still have a peak at its molecular mass.
and even then with your H2O and OH reasoning you're hoping that those ions are actually produced, you need to write that down too.

[vagrantshades]

For 4d,
you could say that if you run the sample through mass spec, you can find its molecular mass, and compare that with propyl proponaotes molecular mass,
Right?

that's what i said

yeahhh bru!

But how does that ensure that it's PURE? :/ Because wasn't it asking how to ensure that it's PURE propyl propanoate?

[illuminati]

can ethanol be (aq)?

would that propyl propanoate by liquid?

could you use HPLC to seperate? (cos you wouldn't want vaporised propyl propanoate!)

okay states is only a problem in exams if you've gotten it COMPLETELY wrong.
For GC the goal is to vaporise ....
GC is used for Mr< 300 from what i remember, HPLC could also be used.

[WhoTookMyUsername]

i specifically talked about OH and H20

i guess no way to ensure perfectly pure, but there would be OH and and H20 ions quite commonly from those i think?/

[illuminati]

i specifically talked about OH and H20

i guess no way to ensure perfectly pure, but there would be OH and and H20 ions quite commonly from those i think?/

It's a tough one. The thing with mass spec is that its just so much less reliable than GC and chromatography.
Like you could put IR there, and say if you see a spike at O-H then its not pure. but thats really iffy compared to others.

[mr.politiks]

5 is most probably D.

For the method of checking the sample is pure, check a similar question in the 2011 exam, question 7. Fractional distillation followed by IR spectroscopy could have been one approach, with the absence of both an OH alcohols and OH acids absorption peaks confirming purity.

Check question 2d i) in the 2010 paper for VCAA's take on the meaning of equivalent protons bonded to an adjacent carbon. Their answer for that question suggest that what they mean when they ask that sort of question is that all the protons on the adjacent carbon are equivalent to each other, but not equivalent to the protons that produced the signal for which they are causing the splitting.

[vagrantshades]

5 is most probably D.

For the method of checking the sample is pure, check a similar question in the 2011 exam, question 7. Fractional distillation followed by IR spectroscopy could have been one approach, with the absence of both an OH alcohols and OH acids absorption peaks confirming purity.

Check question 2d i) in the 2010 paper for VCAA's take on the meaning of equivalent protons bonded to an adjacent carbon. Their answer for that question suggest that what they mean when they ask that sort of question is that all the protons on the adjacent carbon are equivalent to each other, but not equivalent to the protons that produced the signal for which they are causing the splitting.

I still don't understand how it can only be D, considering that the secondary structure can only be maintained with hydrogen bonds between -NH and -CO on the amide linkage and not anywhere else in the amino acids. Because statement II doesn't account for this, it isn't entirely true.

[illuminati]

5 is most probably D.

For the method of checking the sample is pure, check a similar question in the 2011 exam, question 7. Fractional distillation followed by IR spectroscopy could have been one approach, with the absence of both an OH alcohols and OH acids absorption peaks confirming purity.

Check question 2d i) in the 2010 paper for VCAA's take on the meaning of equivalent protons bonded to an adjacent carbon. Their answer for that question suggest that what they mean when they ask that sort of question is that all the protons on the adjacent carbon are equivalent to each other, but not equivalent to the protons that produced the signal for which they are causing the splitting.

I still don't understand how it can only be D, considering that the secondary structure can only be maintained with hydrogen bonds between -NH and -CO on the amide linkage and not anywhere else in the amino acids. Because statement II doesn't account for this, it isn't entirely true.

The statement isn't false.
Because secondary structure IS maintained by hydrogen bonding between -NH and -CO.

[Nobby]

Why is the stearic acid oxidation equation worth 2 marks? States?

[BlueSky_3]

@Illuminati: 6.(b). AES is also acceptable right?

[charmanderp]

Why is the stearic acid oxidation equation worth 2 marks? States?

Realising that this form of oxidation is the same as combustion and balancing, presumably. As well as states, along with other questions.

[charmanderp]

@Illuminati: 6.(b). AES is also acceptable right?

Not at all! So long as you explained it properly.

EDIT: AES is acceptable. I swear your post phrased the question differently when I replied to it...

[BlueSky_3]

@Illuminati: 6.(b). AES is also acceptable right?

Not at all! So long as you explained it properly.

Wait are you being sarcastic? Cause you've scared the living daylight out of me.

[Shenz0r]

@Illuminati: 6.(b). AES is also acceptable right?

Not at all! So long as you explained it properly.

Wait are you being sarcastic? Cause you've scared the living daylight out of me.

You wouldn't use AES - that's used more often for identifying elements rather than organic compounds

[charmanderp]

@Illuminati: 6.(b). AES is also acceptable right?

Not at all! So long as you explained it properly.

Wait are you being sarcastic? Cause you've scared the living daylight out of me.

You wouldn't use AES - that's used more often for identifying elements rather than organic compounds

This is question 6b, where you have to explain a spectroscopic technique. So AES is acceptable.