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Edexcel - Chemistry Unit 2 - 4 June 2013

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nice I am on in topic 2.7 hahah, so scared earlier, but got alot done today, it was really easy, I love chemistry...but I hate edexcel lol.

Reply 261

Cerdic

I don't think fecked quite describes my situation for unit 2. Anyone else really nervous? :colondollar:

Reply 262

phaseshift

Original post by adi19956

I don't think fecked quite describes my situation for unit 2. Anyone else really nervous? :colondollar:

Yep, but thats only because Edexcel can spew up any old topic and try to pass it off as chemistry - ref. baking soda in Unit 1 exam. :tongue:

Reply 263

SKK94

These questions are from the June 2010 paper. Could someone explain them please? :smile:

This Q19 (f)(i) 2nd Titre value = 27.95cm3
av.png.jpg

(edited 10 years ago)

Reply 264

Relaxedexams

Original post by SKK94

These questions are from the June 2010 paper. Could someone explain them please? :smile:

This Q19 (f)(i) 2nd Titre value = 27.95cm3
av.png.jpg

The first one is B I think. As the reaction progresses, the amount of product Y increases, and the amount of reactant X decreases untill equilibrium is reached. After this point the amount of both reactants and products remains the same. Also, the rate of decrease of X and the rate of increase of Y are not constant.

The second one should be 27.85-28.05. The total error is 2 (0.05) which is 0.1. Add and subtract 0.1 to 27.95 to get the range.

Posted from TSR Mobile

(edited 10 years ago)

Reply 265

Baraf

Guys I have noticed the specification does not mention many points that are in the Facer book, such as the diagram of the shape of ice and how it is different in density to water, it is not mentioned in the spec but its in the book. should I cover that ?

Reply 266

phaseshift

Original post by Baraf

The George Facer book has far too much information on in relation to the specification - if it isn't in the spec, then by all means read over it and get a general idea, but dont prioritise it over explicitly mentioned material.

Reply 267

charlieejobson

what topic does everyone find the hardest?

Reply 268

charlieejobson

has anyone got a table or something with all the different reactions we need to know?? if you have that'd be great and i'd really appreciate it if you could upload it because oh my god there is a lot to remember

Reply 269

phaseshift

Original post by charlieejobson

This is something I knocked up to help me memorize the reaction pathways, you obviously have to fill in the details. :tongue:

The main ones to remember is the Amine - Haloalkane - Alcohol pathway, that seems to be a favorite to test.

**DISCLAIMER** This is for Unit 4/5 too, so fyou can ignore the Nitriles/Acyl Chlorides/Esters etc. **DISCLAIMER**

Reaction Pathways.docx80.5KB

Reply 270

Lili94

Im confused, why can HF only form one H bond per molecule if it has 3 lone pairs of electrons?

Reply 271

SKK94

Original post by Relaxedexams

Thanks!!

Regarding the first question, how would the graph differ if the reaction was 2X <--> Y ?
Will the line for X just be higher?

Reply 272

posthumus

Original post by Lili94

Im confused, why can HF only form one H bond per molecule if it has 3 lone pairs of electrons?

There's no lone pair of electrons... I think you may be forgetting that 1st/1s shell in hydrogen can only hold 2 electrons :tongue:

Reply 273

Lili94

Original post by posthumus

There's no lone pair of electrons... I think you may be forgetting that 1st/1s shell in hydrogen can only hold 2 electrons :tongue:

but i thought there are three lone pairs on the fluorine? why can't there be a hydrogen bond to each one?

Reply 274

Locked_box

Original post by Lili94

but i thought there are three lone pairs on the fluorine? why can't there be a hydrogen bond to each one?

I'm pretty sure they can only be bonded dative covalently as they are lone pairs, not unpaired electrons

Reply 275

posthumus

Original post by Lili94

but i thought there are three lone pairs on the fluorine? why can't there be a hydrogen bond to each one?

Oh damn I'm such a moron :colondollar:

I think because there aren't enough hydrogens to bond to the Fluorine, so I would say on average there can be only 1 hydrogen bond between HF molecules.

Reply 276

Lili94

Original post by Locked_box

I'm pretty sure they can only be bonded dative covalently as they are lone pairs, not unpaired electrons

Original post by posthumus

Oh damn I'm such a moron :colondollar:

I think because there aren't enough hydrogens to bond to the Fluorine, so I would say on average there can be only 1 hydrogen bond between HF molecules.