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OCR F324-June 2013 Chemistry

OP

Shouldn't be, rain should be able to hydrolyse it just fine :P

p-orbitals overlap to form pi bonds, creating electron clouds above and below the plane. All the bonds are the same and are therefore the same length.

hahaha true :smile:

correct

my turn

Reply 1641

mrmccarl

hi guys do we need to know how to make tollens reagent? and if so...how is it done?

cheers

Reply 1642

kevloui

Original post by otrivine

hahaha true :smile:

correct

my turn

Explain what it is meant by the Mobile Phase

Original post by mrmccarl

hi guys do we need to know how to make tollens reagent? and if so...how is it done?

cheers

Yes you do, Its made by reacting Silver Nitrate with Ammonia, with heat

Reply 1643

mrmccarl

Original post by kevloui

Explain what it is meant by the Mobile Phase

Yes you do, Its made by reacting Silver Nitrate with Ammonia, with heat

thanks mate

Reply 1644

otrivine

OP

14

Original post by kevloui

Explain what it is meant by the Mobile Phase

Yes you do, Its made by reacting Silver Nitrate with Ammonia, with heat

Mobile phase is the phase in which the chromatography move

Reply 1645

MathsNerd1

17

Just did Jan 2013 and got 56/60!! If only this result would happen on Wednesday then I'll be set!! :biggrin:

Reply 1646

Mus1995

Original post by MathsNerd1

Just did Jan 2013 and got 56/60!! If only this result would happen on Wednesday then I'll be set!! :biggrin:

I need 85/90 UMS so on that paper I'd need 60/60. :frown:

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Reply 1647

MathsNerd1

17

Original post by Mus1995

I need 85/90 UMS so on that paper I'd need 60/60. :frown:

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My god!! Best of luck with that and I need as high as possible to get my A grade and maybe the A* grade, so I'm going to just aim for 56+ and a hardish paper to make up for it :smile:

Reply 1648

thers

5

Actually you don't need to know how to make tollen's reagent - it used to be on the old spec but now its not on this spec.

Reply 1649

Mus1995

Original post by MathsNerd1

My god!! Best of luck with that and I need as high as possible to get my A grade and maybe the A* grade, so I'm going to just aim for 56+ and a hardish paper to make up for it :smile:

I need 29/90 for an A. :P so if I miss the A* I can still fail the paper and get an A.

The coursework ****ed me over. 36/40 raw looking to be around 48/60 UMS. 4 raw marks for 12 UMS. Ridiculous. :/

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Reply 1650

Rectifydude

This may sound silly, but how do you actually draw Optical isomers of Chiral Carbons, i always seem to get the functional groups on the wrong sides, is there a general rule?

Reply 1651

MathsNerd1

17

Original post by Mus1995

I need 29/90 for an A. :P so if I miss the A* I can still fail the paper and get an A.

The coursework ****ed me over. 36/40 raw looking to be around 48/60 UMS. 4 raw marks for 12 UMS. Ridiculous. :/

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That's just not fair! I need like a high A just to guarantee my A -.- This is getting back at me for getting a C last year and yeah I got the same coursework mark too :-/

Reply 1652

thers

5

Heres a question for you all:

What conditions/reagents are required to prepare propylamine from 1-chloropropane? [2]

Suggest a possible disadvantage of using this method and state one possible way to avoid this. [2]

Suggest two reasons why water cannot be used as a solvent in this reaction. [2]

Reply 1653

Mus1995

Original post by thers

Heres a question for you all:

What conditions/reagents are required to prepare propylamine from 1-chloropropane? [2]

Suggest a possible disadvantage of using this method and state one possible way to avoid this. [2]

Suggest two reasons why water cannot be used as a solvent in this reaction. [2]

Excess NH3 and ethanol solvent. Heat under reflux.

The byproduct HCl/NH4+Cl- is acidic? So it needs to be neutralised with a base which you have, NH3? I dunno.

An ethanol solvent is used instead of water. Is it because it would interact with HCl? Dipoles etc.

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Reply 1654

otrivine

OP

14

Original post by thers

Heres a question for you all:

What conditions/reagents are required to prepare propylamine from 1-chloropropane? [2]

Suggest a possible disadvantage of using this method and state one possible way to avoid this. [2]

Suggest two reasons why water cannot be used as a solvent in this reaction. [2]

1) Reagents= excess (conc) NH3 and ethanol as solvent, conditions= heat under reflux

2) can undergo further multiply nucleophilic substitution so does not give the desired product , a possible way to avoid this is to add excess NH3 to minimise further substitution

3) Because addition of water will result in hydrolysis and could split the propylamine/1-chloropropane into 2 monomers, h2o does not result in the amine forming , as no nitrogen is present in H2O

Reply 1655

thers

5

Both right on first part
Second part otrivine is correct
Third part is because water can act as a nucleophile so hydrolysis could take place forming an unwanted alcohol. I was only supposed to put one reason, not two - my mistake.

Reply 1656

otrivine

OP

14

Original post by thers

Both right on first part
Second part otrivine is correct
Third part is because water can act as a nucleophile so hydrolysis could take place forming an unwanted alcohol. I was only supposed to put one reason, not two - my mistake.