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OCR F324-June 2013 Chemistry

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Reply 2440

V__005

Original post by MathsNerd1

C6H6 + HNO3 (conc sulphuric acid catalyst) ---> C6H5NO2 + H20 and I'm not sure about the atom economy, would it be 50%?

Atom economy is 87.4% ??

Reply 2441

physicshelp123

Original post by sals1234

Hey guys, can someone please explain to me why in question 5biv (feature that causes stereoisomersism in citral) we have to circle the double bond that's on the right and not the one on the left? Here's the link to the paper: http://www.ocr.org.uk/Images/58126-question-paper-unit-f324-rings-polymers-and-analysis.pdf

Thank you :smile:

with the one on the left, the lefter carbon is attached to 2 ch3 groups therefore it has no isomerism :smile:

basically if you rotate the two groups you still have the exact same thing therefore it must be the on the right :smile:

hope this helps kinda

Reply 2442

k54g00

Original post by Onkar-M

So TLC - adsorption, G-C = rel. solubility?

Satsriakal Ji!

Substances adsorb onto a SOLID stationary phase, but are separated by RELATIVE SOLUBILITY on a liquid stationary phase.

TLC- Solid- Adsorption
GC- Liquid- Rel. Solubility.

But, if i'm not mistaken, can't GC also have a solid inert support, thus separating by adsorption?

Reply 2443

sals1234

Original post by Jodie_668

Because the carbon that is on the left on the double bond of the left (I hope that makes sense, ahaha) is bound to the same groups (bound to two CH3). For E/Z isomerism, each carbon in the C=C must be bound to two different groups. :smile:

Ah thank you!! :smile:

Reply 2444

Zzzyax

good luck everyone with the exam tomorrow

Reply 2445

Jodie_668

Hi, does anyone know if when you hydrolysis peptide of amide bonds using acid, does the NH2 become +NH3? Some of my notes say that it does and others don't :s-smilie:

Reply 2446

thers

Original post by MathsNerd1

Thanks and yeah I remember that, just thought you wanted a value instead :colondollar:

That's not the answer - it was a hint to how you work out the atom economy so you can now work out the value. :smile:

Reply 2447

_HabibaH_

Original post by Onkar-M

So TLC - adsorption, G-C = rel. solubility?

GC depends on the state of the stationary phase. if it's solid, adsorption. If it's liquid, relative solubility. Read the state but usually it is a liquid state.

Reply 2448

mrmccarl

Original post by k54g00

Yes you are right GC can separate components with either adsorption or rel solubility...depends what stationary phase the paper tells you.

Reply 2449

mrmccarl

Original post by Jodie_668

Hi, does anyone know if when you hydrolysis peptide of amide bonds using acid, does the NH2 become +NH3? Some of my notes say that it does and others don't :s-smilie:

yes it becomes nh3+ due to 2h+ from the acid and h2o.

Reply 2450

_HabibaH_

Original post by Jodie_668

Hi, does anyone know if when you hydrolysis peptide of amide bonds using acid, does the NH2 become +NH3? Some of my notes say that it does and others don't :s-smilie:

If acid is in excess, then yes it will. If it is not excess, then no it won't. If the amount is not specified then they should take either answer.

Reply 2451

MathsNerd1

Original post by thers

That's not the answer - it was a hint to how you work out the atom economy so you can now work out the value. :smile:

Okay then, thanks :smile:

Do you have any other questions for me to tackle?

Reply 2452

Gulzar

Original post by mrmccarl

Yes you are right GC can separate components with either adsorption or rel solubility...depends what stationary phase the paper tells you.

How much further detail do we need to know including limitation and retention time?

Reply 2453

thers

Original post by MathsNerd1

Okay then, thanks :smile:

Do you have any other questions for me to tackle?

What two observations would you see if you reacted bromine with phenol?

Reply 2454

_HabibaH_

Original post by Varsh05

Atom economy is 87.4% ??

Hi, how did you work out that atom economy? And are there any other AS equations that I should know? Thank you in advance :smile:

Reply 2455

Jodie_668

Original post by mrmccarl

yes it becomes nh3+ due to 2h+ from the acid and h2o.

Original post by _HabibaH_

If acid is in excess, then yes it will. If it is not excess, then no it won't. If the amount is not specified then they should take either answer.

Thanks so much! :biggrin:

Reply 2456

MathsNerd1

Original post by thers

What two observations would you see if you reacted bromine with phenol?

The bromine water would be decolourised and a white precipitate will be formed?

Reply 2457

thers

Original post by Varsh05

Atom economy is 87.4% ??

Yes

Reply 2458

dadams2

So panicked- desperately in need of an A* tomorrow to make my offer since c4 kicked my a** today. Hopefully tomorrow will be a nice paper and I won't make any of my patented mistakes :rolleyes: