I put chromatography because fractional distillation isn't on the unit 4 spec but...oh wait, half this paper had nothing much to do with our spec anyways -_-

Fractional distillation should be fine.

Reply 1723

Suits101

Original post by SubwayLover1

yeye

Sodium ethanoate has ionic bonding between (O- and Na+) so if you heated it ... surely you would be able to distill off the alcohol ?

I'm going to be honest I don't know.

It was only one mark so I'm trying to not worry about it but if what you said is true then I suppose so! :smile:

Reply 1724

SubwayLover1

Original post by Suits101

I'm going to be honest I don't know.

It was only one mark so I'm trying to not worry about it but if what you said is true then I suppose so! :smile:

Sorry pahah! I need an A* in chem so I am stressing D: !

Reply 1725

Jonnyss

Original post by Suits101

That's exactly right

Can it be HCl and not H2SO4

Reply 1726

neelt

What would 45/100 be lol

Reply 1727

emma_1111

Anyone have an unofficial mark scheme?

Reply 1728

FireBLue97

URGENT Can someone please put the topics of each questions in order up URGENTLY NEED THIS

Reply 1729

Capsicle102

Original post by Suits101

I said the rate equation was the same and stated that iodine was not in it or whatever hence rate remains the same but I rushed it - any marks do you think?

Sorry, genuinely have no clue (not even sure if what I wrote was right lol XD) Based on what I know from the syllabus, I'd guess that's too vague to count as clarification, because the question was more linked to whether or not increasing the concentration of ethanoic acid would have an effect on the rate equation

Reply 1730

Suits101

Original post by FireBLue97

URGENT Can someone please put the topics of each questions in order up URGENTLY NEED THIS

1. Acids/bases
2.
3.
4.
5.
6.
7. Kinetics
8. Kinetics
9. NMR

That's all that I remember sorry.

Reply 1731

FireBLue97

Original post by Suits101

1. Acids/bases
2.
3.
4.
5.
6.
7. Kinetics
8. Kinetics
9. NMR

That's all that I remember sorry.

Mate thats more questions than any1 can remember so thanxs.

Reply 1732

Suits101

Original post by FireBLue97

Mate thats more questions than any1 can remember so thanxs.

I can remember the topics but not in order sadly!

Reply 1733

ahsan_ijaz

Hi,

I have a Q on chem 5 now as i think you need to work on chem 5 now as its ch4 is done!
THE Q is that in thermodynamics when we have a pure ionic model the experiment and theorotical values dont differ much but when we have a compound with covalent character the experimental date is more exothermic? Taking this into account and applying to periodicity and the fact that AL203 has a partially covalent character as the electron cloud is distorted and so it has partially covalent and ionic bonding , why isn't the melting point of al203 higher than na2o or mgo

i understand that the charge increases so stronger ionic bond etc thus the highest melting point of oxides is mgo but i wanna know why its not al2o3 considering its a bit covalent?
is covelent bonding stronger or ionic?

Reply 1734

ELCRE

Original post by gcsesurvivor

Honestly likely that I will have gotten around 30 marks on that paper after getting almost 80 on every other past paper that I have done. I waited for this thread to die down from the initial anger in order to ask, does anybody have any idea how many UMS 30 marks would be or what would be needed for a D grade in this exam, as I'm needing a B overall to get into uni. Luckily, I have much better subjects to fall back on. My offer is ABB and I am seriously hoping universities will take this awful exam into consideration and let us in with, in my case, ABC.

I was wondering the exact same thing, my mark is no more than 30-40 marks. Someone told you get an automatic U if you fail one of your units, or do I still have a chance to make it up with unit 5?

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Reply 1735

mariapops

[QUOTE=Cave Felem;65829287]Did nobody else say fractional distillation? The alcohol has a different boiling point to the other compounds so it should be legit right?

I said this!!

Reply 1736

Cadherin

Original post by ELCRE

That's total rubbish - your final total UMS score will determine your grade.

Reply 1737

SirRaza97

I don't really understand why people found this paper outrageous. I thought it was okay. It wasn't easy but it wasn't hard either. They just tried really hard to over complicate questions. I didn't do brilliantly as well but I think everyone needs to chill.

Letting this paper get to your head will seriously effect your performance in future papers. Focus on CHEM5.

Reply 1738

SirRaza97

Original post by ahsan_ijaz

Generally ionic character is stronger than covalency but it really depends what you are comparing with what. Some covelant bonds are much stronger than ionic bonds and vice versa.

I think to answer your question (i am taking a guess) is that the covelant character in aliminum oxide is little compared to the ionic character. This slightly weakens the ionic bonding which is prescedent and causes it to have a lower melting point. Or, the idea of shielding and ionic radius of each element comes into play to effect the attraction between the two. Aluminium has more shielding due to an electron being in the 3p orbital.

(edited 7 years ago)

Reply 1739

DDan123

Original post by SirRaza97

Agreed. But I have no idea what to expect for Chem 5 now. I felt confident for both units, but the exam on Tuesday completely shocked me so idek...

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