OCR F324-June 2013 Chemistry

OP

Original post by reneetaylor

How do photodegradeable polymers operate?

Photodegrable polymers are synthetic polymers and are resistant when exposed in sunlight for a pre-longed period of time. They contain a carbonyl group (functional group) within the backbone and they absorb light energy/sun light which results in the polymer being broken down into smaller fragments.

Reply 762

reneetaylor

11

Original post by otrivine

Photodegrable polymers are synthetic polymers and are resistant when exposed in sunlight for a pre-longed period of time. They contain a carbonyl group (functional group) within the backbone and they absorb light energy/sun light which results in the polymer being broken down into smaller fragments.

Correct, nicely put :smile:

Reply 763

OP

Original post by reneetaylor

Correct, nicely put :smile:

thanks !

Describe what the peaks represent in a carbon-13 spectrum (1)

Reply 764

Natalie21

15

Original post by otrivine

thanks !

Describe what the peaks represent in a carbon-13 spectrum (1)

A carbon environment. No. of peaks = no of different carbon environments.

Reply 765

OP

Original post by Natalie21

A carbon environment. No. of peaks = no of different carbon environments.

yes correct.

my turn :smile:

Reply 766

I'm back now, can I join in?

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Reply 767

reneetaylor

11

Original post by MasterYi

Can someone expalin to me the meaning of mobile phase and stationary phase. I 've seen a couple of vagues definitions and I'm not sure what to use as a go to definition.

The stationary phase is where molecules from the samples can adsorb to, it can be a solid or a liquid supported on a solid, silica gel is an example of a stationary phase.

The mobile phase is either a liquid or gas, which brings the samples with it as it travels up the stationary phase.

Reply 768

OP

Original post by MathsNerd1

I'm back now, can I join in?

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wow!! you came :biggrin:

ask me

Reply 769

Original post by otrivine

wow!! you came :biggrin:

ask me

Well I did say I would come back once I'm more confident with the content, so here I am and okay, start off easy then.

Show the mechanism of halogenation to the benzene ring in diagrams and explain why a halogen carrier is needed. (4)

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Reply 770

OP

Original post by MathsNerd1

Well I did say I would come back once I'm more confident with the content, so here I am and okay, start off easy then.

Show the mechanism of halogenation to the benzene ring in diagrams and explain why a halogen carrier is needed. (4)

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do you want me to draw it in paper?

Halogen carrier is needed because benzene is stable and has a lower pie electron density and therefore there is less polarisation of halogenation and therefore, a halogen carrier is needed.

Reply 771

MasterYi

Original post by reneetaylor

The stationary phase is where molecules from the samples can adsorb to, it can be a solid or a liquid supported on a solid, silica gel is an example of a stationary phase.

The mobile phase is either a liquid or gas, which brings the samples with it as it travels up the stationary phase.

Thanks.

Can't even give you a thumbs up because I've given too many to you already.

Reply 772

Original post by otrivine

do you want me to draw it in paper?

Halogen carrier is needed because benzene is stable and has a lower pie electron density and therefore there is less polarisation of halogenation and therefore, a halogen carrier is needed.

Yeah if you wouldn't mind and that's correct :smile:

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Reply 773

reneetaylor

11

Original post by MasterYi

Thanks.

Can't even give you a thumbs up because I've given too many to you already.

Haha, thanks!
No problem, glad I helped :smile:

Reply 774

Original post by otrivine

here, mechanism

Correct, now my turn :biggrin:

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Reply 775

OP

Original post by MathsNerd1

Correct, now my turn :biggrin:

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Describe in words the mechanism of Nucleophilic Addition (4)

Reply 776

OP

Original post by MasterYi

Thanks.

Can't even give you a thumbs up because I've given too many to you already.

Hi want to join :smile:

Reply 777

Original post by otrivine

Describe in words the mechanism of Nucleophilic Addition (4)

Okay well it occurs in aldehydes and ketones when they react with sodium borohydride and okay the electron deficient carbon atom in the polar C=O bond is attacked by the OH-. The lone pair of electrons forms a bond with the carbon atom and at the same time the pi bond breaks to produce a negatively charged intermediate. This then donates an electron pair to a hydrogen atom from a water molecule to for a dative covalent bond and a OH- ion.

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Reply 778

OP

Original post by MathsNerd1

Okay well it occurs in aldehydes and ketones when they react with sodium borohydride and okay the electron deficient carbon atom in the polar C=O bond is attacked by the OH-. The lone pair of electrons forms a bond with the carbon atom and at the same time the pi bond breaks to produce a negatively charged intermediate. This then donates an electron pair to a hydrogen atom from a water molecule to for a dative covalent bond and a OH- ion.

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Perfect!

my turn

Reply 779