OCR AS - Chemistry Unit F322 - Chains, energy and resource - REVISION!

could some detail what we need to know about Green Chemistry. cheers

Reply 301

Bright

11

Original post by timkench

anyone else done the june 2010 paper and found it really hard?

I haven't really done past papers yet but I have looked at them and found them hard!

Unit 1 was so easy I used to get full marks without revision but this is so different! :'(

I feel so behind compared to everyone on this thread! ahhhhhhhhhhhh :l :frown:

Reply 302

J DOT A

1i)What is Ethyl-1,2-diol + Propanoic acid... List the conditions and reagents required for the reaction.

ii)Why does Alcohol dissolve in water
iii) Suggest why Methan-1-ol dissolves in water but Pentan-1-ol does not.

iv) Which is more sustainable, Fermentation of glucose or Hydration of Ethene, and explain why.

Reply 303

ChessMister

12

Original post by J DOT A

1i)What is Ethyl-1,2-diol + Propanoic acid... List the conditions and reagents required for the reaction.

ii)Why does Alcohol dissolve in water
iii) Suggest why Methan-1-ol dissolves in water but Pentan-1-ol does not.

iv) Which is more sustainable, Fermentation of glucose or Hydration of Ethene, and explain why.

I think you mean Ethane-1,2-diol, which makes ethyl propanoate
H2SO4 catalyst & heat

Reply 304

tripodd

The book says they can ask us for a mechanism with h2o acting as a nucleophile, how on earth would we do that? :/l

Reply 305

Joshc93

subscribed out of panic

Reply 306

Original post by warthogBE

Acrobat is being stupid - well, not really, but the file is too large to upload, so here you go:

www.thestudentroom.co.uk/attachment.php?attachmentid=98906&d...

Cheers-sorry i'm a week late, got too caught up in the studying

Reply 307

Original post by J DOT A

1i)What is Ethyl-1,2-diol + Propanoic acid... List the conditions and reagents required for the reaction.

ii)Why does Alcohol dissolve in water
iii) Suggest why Methan-1-ol dissolves in water but Pentan-1-ol does not.

iv) Which is more sustainable, Fermentation of glucose or Hydration of Ethene, and explain why.

*Its esterification. Conditions are heat and concentrated sulphuric acid as a catalyst.
*Hydrogen bonding occurs between water and alcohol molecules
*Fermentation, as glucose can be made, so it is a renewable source of energy. Ethene is obtained from crude oil, which can run out soon, so isn't sustainable.

Reply 308

Pandit Bandit

Original post by tripodd

The book says they can ask us for a mechanism with h2o acting as a nucleophile, how on earth would we do that? :/l

I need help on that 1 too!

Reply 309

Original post by Pandit Bandit

I need help on that 1 too!

I assume that means the H20 breaks up into an OH ion and H atom. Then you can just use the OH ion is the nucleophile. I have never heard of that before though...

Reply 310

student777

Original post by tripodd

The book says they can ask us for a mechanism with h2o acting as a nucleophile, how on earth would we do that? :/l

I don't think that's on the syllabus... In any case, if it is just use the OH- as the nucleophile. It doen't really matter if it comes from KOH or NaOH or H2O, it's still a nucleophile so the mechanism is the same!

Reply 311

Original post by Pandit Bandit

I need help on that 1 too!

you should use OH^- as the nucleophile

Reply 312

i need help with Hiss diagrams...could someone say which way the arrows point if we are given information for "enthalpy change of formation" and asked to work out 'enthalpy change of combustion'. And vise versa.

Reply 313

Bond enthalpy is the energy change to break 1 mole of a covalent bond in the gaseous state.

Reply 314

Original post by Flint_09

i need help with Hiss diagrams...could someone say which way the arrows point if we are given information for "enthalpy change of formation" and asked to work out 'enthalpy change of combustion'. And vise versa.

For enthalpy of combustion, the bottom box has to be carbon dioxide and water. Therefore, point both arrows down to the bottom box. Don't forget to put balancing numbers in, and use them for calculating the enthalpy changes.

For enthalpy of formation, its the opposite-the arrows point upwards. This is because you put all the elements in the reaction in the bottom box, so arrows go from the bottom box to the two other boxes.

I hope you can understand that...please tell me if you cant so i can try and explain better.

Reply 315