Edexcel - Chemistry Unit 2 - 4 June 2013

hi guys, Im actually findin this sooo hardd... :'(

Especially long experiment qustions like in the june 2010 paper section B q19
These are supposed to be simple i think but i just end up guessing what I have to do which obv aint good :frown:

Got bio on mon chem on tue and physics on wed. Im screwed!

Reply 421

Mimi85

Original post by Goods

I do AQA must be different boards

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ohh okay

Reply 422

Mimi85

so guys what books do u use ?? how many ?

Reply 423

Mimi85

Original post by Gnome :)

It's either on the page before this one, or the one before that. It would take 2 mins to find it. I worry for you if this is the attitude you take towards your revision.

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sure...

Reply 424

Locked_box

6

I use one book that I don't really care for (edexcel textbook for AS chem) and the rest is notes, chemguide and papers :smile:

Reply 425

felicity95

hey guys I need some help.

Please can someone explain the difference between:

Permanent dipole-permanent dipole
Instantaneous dipole-induced dipole
Induced dipole-induced dipole
instantaneous dipole -instantaneous dipole.

Ive seen these terms thrown around a lot in different contexts and am very confused. Thanks.

ooh also, what happens to reactivity down group 2 and 7 and why? (If that makes sense)

Reply 426

Locked_box

6

Original post by felicity95

hey guys I need some help.

Please can someone explain the difference between:

Permanent dipole-permanent dipole
Instantaneous dipole-induced dipole
Induced dipole-induced dipole
instantaneous dipole -instantaneous dipole.

Ive seen these terms thrown around a lot in different contexts and am very confused. Thanks.

ooh also, what happens to reactivity down group 2 and 7 and why? (If that makes sense)

right...a little confusing but here's what I know:
London dispersion forces create instantaneous dipoles which induce dipoles in neighboring atoms/molecules. Permanent dipoles are molecules which are polar. I suppose the way you've linked them together suggests how they're bonded together?

Reply 427

felicity95

Original post by Locked_box

right...a little confusing but here's what I know:
London dispersion forces create instantaneous dipoles which induce dipoles in neighboring atoms/molecules. Permanent dipoles are molecules which are polar. I suppose the way you've linked them together suggests how they're bonded together?

hummm I understand what youre saying about the permanent dipoles in molecules which are polar, but what are London dispersion forces. Do all molecules contain London dispersion forces?

Reply 428

Jayqwe

1

Do we need to know all the stats and case studies in the green chemistry chapter? Theres tons of 'BS' in it..

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Reply 429

felicity95

Ok just read in the edexcel blue book that the boiling temperature of HCl is greater than that of HBr or HI due to greater dipole-dipole interactions, yet on the graph HCl has a bpt of -90 whilst HBr has a bpt of -70 and Hi of -40. Surely the bpts of HBr and HI are higher, because as you go from HCl to HI the size of the electron cloud increases and hence the van der waals forces increase. is it a mistake in the book?

Reply 430

johnny-marr

Original post by Jayqwe

Do we need to know all the stats and case studies in the green chemistry chapter? Theres tons of 'BS' in it..

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No not specifics, the textbook often elaborates far too much. Just need some examples why biofuels might be better than fossil fuels, disadvantages of biofuels, the whole ozone thing (the O3 free radial reaction you need to know) and how CFCs along with NOs destroy ozone...the section C is usually a green chemistry related question but they will give you specific information.

Reply 431

zyxwvuts

1

Question: are london forces or permanent dipole-dipole interactions stronger?

Reply 432

Kurraiyo

7

Original post by samsimmons

Question: are london forces or permanent dipole-dipole interactions stronger?

I asked my chemistry teacher the same thing, she said you can't really compare those two because the strength of london forces are greatly variable. Large atoms/molecules --> stronger london forces. whereas dipole-dipole interactions are not that variable...basically it depends on the size of the molecules held together by London forces

Reply 433

Jayqwe

1

What is the proper definition of a greenhouse gas? Is it a gas that absorbs IR radiation or a gas that traps ir radiation in the earths' atmosphere?

Reply 434

Londrinna

Hey guys, can anyone explain to me what is and how to work out electrical conductivity of titration mixtures? :s please

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Reply 435

Londrinna

Original post by Jayqwe

What is the proper definition of a greenhouse gas? Is it a gas that absorbs IR radiation or a gas that traps ir radiation in the earths' atmosphere?

I would say its a gas that absorbs IR radiation, and so the IR radition is said to be 'trapped' in the Earths atmosphere (as these gases are found in the atmosphere) ...

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(edited 10 years ago)

Reply 436

zyxwvuts

1

Original post by Kurraiyo

I asked my chemistry teacher the same thing, she said you can't really compare those two because the strength of london forces are greatly variable. Large atoms/molecules --> stronger london forces. whereas dipole-dipole interactions are not that variable...basically it depends on the size of the molecules held together by London forces

Thank you

Reply 437

Priya08

Original post by Londrinna

I would say its a gas that absorbs IR radiation, and so the IR radition is said to be 'trapped' in the Earths atmosphere...

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in one of the papers it has come up I thinkkk u have to say a gas that traps ir radiation in the atmosphere AND reflects it back onto the earth

Reply 438

phaseshift

12

Original post by senz72

Just the whole halogenoalkane mechanism business?

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So, specifically, how nucleophiles attack halogenoalkanes?

Original post by Khurc003

hi guys, Im actually findin this sooo hardd... :'(

Especially long experiment qustions like in the june 2010 paper section B q19
These are supposed to be simple i think but i just end up guessing what I have to do which obv aint good :frown:

Got bio on mon chem on tue and physics on wed. Im screwed!

What bits? Keep on swimming. :biggrin:

Original post by Mimi85

so guys what books do u use ?? how many ?

The George Facer book with the Jim Clarke calculations one on the side.

Original post by Londrinna

Hey guys, can anyone explain to me what is and how to work out electrical conductivity of titration mixtures? :s please

Posted from TSR Mobile

I don't think you need to know the Ecell stuff, that is Unit 5 in A2. You are just expected to have a basic understanding of electrical conductivity - so, when lots of ions are floating about, the conductivity will likely increase.