OCR F324 (Chains, rings and spectroscopy) 28/06/10

Reply 580

uer23

15

The biology paper was horrible, I just hope it's not the same for chemistry. :frown:

Reply 581

_Andrew_

11

Sakujo

Could someone outline the reactions that require concentrated acid and which ones require dilute acid?

Ester hydrolyses is dilute acid, polyamide hydrolysis is conc. We don't get marks for either, the marks come from saying 'aqueous' and 'heating under relux'

Reply 582

Chunkeymonkey62

2

Anyone want to explain NMR in medicine?

Do we need to know about Hazards/Diagnosis

Reply 583

AnniG

1

_Andrew_

Ester hydrolyses is dilute acid, polyamide hydrolysis is conc. We don't get marks for either, the marks come from saying 'aqueous' and 'heating under relux'

I've seen quite a lot of marks scheme where providing you specify dilute you get the mark - ie you don't have to say aqueous.. but to be on the safe side I'll remember to say both!

Reply 584

AnniG

1

Chunkeymonkey62

Anyone want to explain NMR in medicine?

Do we need to know about Hazards/Diagnosis

"explain that NMR spectroscopy is the same
technology as that used in ‘magnetic resonance
imaging’ (MRI) to obtain diagnostic information
about internal structures in body scanners"

Let's be fair, they're not gonna ask much on them! I say this and tomorrow when there's a 10 mark question on MRI scans following a page of pretty pictures of people in MRI scanners I will shoot myself with my mechanical pencil >.< Stupid OCR lol

Reply 585

_Andrew_

11

AnniG

I've seen quite a lot of marks scheme where providing you specify dilute you get the mark - ie you don't have to say aqueous.. but to be on the safe side I'll remember to say both!

Oh right, I'll say both too :wink:

How you feeling about tomorrow? I'm worried about stretch and challenge, or, something really random from AS that I've forgotten

Reply 586

AnniG

1

_Andrew_

Oh right, I'll say both too :wink:

How you feeling about tomorrow? I'm worried about stretch and challenge, or, something really random from AS that I've forgotten

I think I've given up all hope haha.. I'm just worried about what's going to come up! The trouble is I'm fine on the past paper questions but I know the paper will be random in some way. Snap on the synoptic bits - not gonna be very good at those I think I've forgotten everything AS! What about you? I'm sure you'll be fine you seen to know everything!!

Reply 587

Gemmer

AnniG

"explain that NMR spectroscopy is the same
technology as that used in ‘magnetic resonance
imaging’ (MRI) to obtain diagnostic information
about internal structures in body scanners"

Let's be fair, they're not gonna ask much on them! I say this and tomorrow when there's a 10 mark question on MRI scans following a page of pretty pictures of people in MRI scanners I will shoot myself with my mechanical pencil >.< Stupid OCR lol

Maybe in one of the pics the person will have their nostrils closed..

Reply 588

_Andrew_

11

AnniG

I think I've given up all hope haha.. I'm just worried about what's going to come up! The trouble is I'm fine on the past paper questions but I know the paper will be random in some way. Snap on the synoptic bits - not gonna be very good at those I think I've forgotten everything AS! What about you? I'm sure you'll be fine you seen to know everything!!

I'm the same, I do really well on the old spec past papers, but I know there trying to not make the questions like that anymore :mad:

I have a feeling that forming esters from acid anhydrides will come up :dunno:

Reply 589

vertigo.0012

13

Gemmer

Maybe in one of the pics the person will have their nostrils closed..

"This is a person:
{Picture of a person}

This is a person out of an MRI scanner
{Picture of person out of an MRI scanner}

This is a person inside an MRI scanner
{Picture of a person inside an MRI scanner}

What technology does this MRI scanner use to generate an image?"

I'm willing to put money on this question appearing in the exam.

Reply 590

student92

1

Gemmer

I hate it too.. WITH A PASSIONNNN!

Maybe just keep it a little in your head.
Isn't it only 2 steps? :s-smilie:

What is the mechanism? :s-smilie:

Reply 591

flisshg

1

Gemmer

Maybe in one of the pics the person will have their nostrils closed..

Another annoyed biologist. Or maybe an insert with a coloured picture of a molecule we've never studied and an un-related question?

Reply 592

cyborg

Could someone clarify this for me ?

In the hydrolysis of polyamides with acid, does the NH2 ionise as well ?

See the attachment :smile:

- Which answer is correct ?

Thanks

cyborg

Could someone clarify this for me ?

In the hydrolysis of polyamides with acid, does the NH2 ionise as well ?

See the attachment :smile:

- Which answer is correct ?

Thanks

Either.

Reply 594

Noble.

17

cyborg

Could someone clarify this for me ?

In the hydrolysis of polyamides with acid, does the NH2 ionise as well ?

See the attachment :smile:

- Which answer is correct ?

Thanks

Acid-catalysed hydrolysis of a polyamide results in a dioic acid and the salt of the diamine.

Base-catalysed hydrolysis of a polyamide results in the diamine and the salt of the dioic acid. So NH3+ is formed.

Reply 595

cyborg

Thanks for the quick responses :smile:

I was confused because the book leaves it as NH2, but I thought that since we need to know reactions of amines anyway, it would be NH3+.

So for acid hydrolysis: NH3+ and COOH ?

For base hydrolysis: NH2 and COO-Na+ ?

Reply 596

Noble.

17

cyborg

Thanks for the quick responses :smile:

I was confused because the book leaves it as NH2, but I thought that since we need to know reactions of amines anyway, it would be NH3+.

So for acid hydrolysis: NH3+ and COOH ?

For base hydrolysis: NH2 and COO-Na+ ?

Yep.

Reply 597

CreativeBass

What is the reaction for the coupling reaction of the diazonium salt and the phenol

one book says the end product is NaCl + H20
Another says it is +Hcl

Reply 598

Sakujo

14

cyborg

Thanks for the quick responses :smile:

I was confused because the book leaves it as NH2, but I thought that since we need to know reactions of amines anyway, it would be NH3+.

So for acid hydrolysis: NH3+ and COOH ?

For base hydrolysis: NH2 and COO-Na+ ?

Yes but the MS won't be too picky about NH3+ AFAIK