Official AQA AS Chemistry Unit 1 - 23Rd May 2013

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Reply 440

spangie

Original post by lukeetaylorr

Did anyone get 4.03g and 90.3% for purity ? Think I definetly dropped 8marks there ..

I reckon 90.3% is right, most of my friends got that! Not sure about the other answer. Sadly I got neither haha

Reply 441

nath1405

Original post by jodie.irwin27

i said Lithium although i have no idea why.. just remember doing the Jan13 paper and a similar question came up for group 3 and it was sodium.. so i chose the first element in the period :L

surely it was Neon because ionisation energy increases across the period as they become smaller?

Reply 442

smileitsfree

guys wondering about empirical formula of graphane

http://en.wikipedia.org/wiki/Graphane

wiki does not lie.

Reply 443

izzyd16

Original post by The Lawful T.J

Omg. Please tell me you're some super genius :frown:

because I got 46.9% for that purity question..

- Tom

Hey I got around 47 too, have no idea how though! :L

Reply 444

The Lawful T.J

Original post by nath1405

surely it was Neon because ionisation energy increases across the period as they become smaller?

Smaller? You thinking about atomic radius? It's Lithium because the second electron is being removed from the 1s sub level (orbital)... Closer to the nucleus etc.

- Tom

Reply 445

Tom_hess

Original post by nath1405

surely it was Neon because ionisation energy increases across the period as they become smaller?

I'm afraid not, as you're taking an electron out of the 1s shell which has much less shielding that 2p

Posted from TSR Mobile

Reply 446

LaLady

Original post by nath1405

surely it was Neon because ionisation energy increases across the period as they become smaller?

thats the general trend

Reply 447

maik13

relative atomic mass- weighted isotopic mass of an atom relative to 1/2th carbon 12

7 3.4? it was something .4 cant remember

I got 89.9% to yeah 90% too!!!
I got 7 for x

I got C3H

erm the last one was C2H4CL I think

will add to this to make an unoffical mark scheme-let me kow if you disagree

C16H34 for one

Reply 448

tumblrgirl

is the formula for graphene C3H or C4H or CH or something else? :confused:

Reply 449

Tynos

Original post by pearson1995

It was Li because all the other elements in that period were in the same sub level for 2 Electrons being knocked off.

If you look at Li It has 3 electrons therefore knocking 1 off would be normal knocking the second one off would take more energy as less shielding.

Reply 450

jodie.irwin27

Original post by nath1405

surely it was Neon because ionisation energy increases across the period as they become smaller?

it was the SECOND though, if it was first then it would be neon

Reply 451

lukeetaylorr

It's lithium, I put boron for some reason but here
http://www.webelements.com/periodicity/ionisation_energy_2/period_2sp.html

Reply 452

The Lawful T.J

Original post by izzyd16

Hey I got around 47 too, have no idea how though! :L

Omg I'm kinda feeling somewhat better now xD I need 90+ I swear. I got 82 on the first but I lost marks because I was stupid and didn't read question properly! But with this one, it was the fact I didn't know how to answer most questions xD

- Tom

Reply 453

maik13

Original post by Tom_hess

I'm afraid not, as you're taking an electron out of the 1s shell which has much less shielding that 2p

Posted from TSR Mobile

it was 2nd IE so wasnt it Be

Reply 454

Tom_hess

Agree, except graphene might be CH, many of my friends said that, and does wiki(but don't just trust wiki!!:s)

Posted from TSR Mobile

Reply 455

The Lawful T.J

Original post by maik13

72.4

- Tom

Reply 456

nath1405

****ed that exam up then I put AlCl instead of AlCl3 which is just stupid, i put 3rd ionisation energy instead of 2nd which is even worse, could not do the purity question! ****ed.

Reply 457

The Lawful T.J

Original post by Tom_hess

Agree, except graphene might be CH, many of my friends said that, and does wiki(but don't just trust wiki!!:s)

Posted from TSR Mobile

I just realised that every carbon attached to the main carbon atom had a hydrogen on too.. So it must be CH ><

- Tom

Reply 458

smileitsfree

Original post by Tom_hess

Agree, except graphene might be CH, many of my friends said that, and does wiki(but don't just trust wiki!!:s)

Posted from TSR Mobile

http://en.wikipedia.org/wiki/Graphane

trust wiki bro.

Reply 459

jodie.irwin27

Original post by Tom_hess

Agree, except graphene might be CH, many of my friends said that, and does wiki(but don't just trust wiki!!:s)

Posted from TSR Mobile

the thing is though.. it stated in the question that there were 3 carbon-carbon bonds and 1 carbon-hydrogen bond... so it must have been C3H? If it was CH then they would have stated in the question that there were 2 c-c bonds and 2 h-c bonds.. :/