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AS Chemistry- helping each other out!

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I've heard that exam boards actually moderating TSR so anyone who is identified and who does post messages like such may get disqualified.
Original post by KINGYusuf
Guys which molecules have permanent dipole-permanent dipole bonds? Is it only the polar ones?


Yep, pretty much any polar molecule can form permanent dipole-dipole interactions. Though just to be on the safe side, I wouldn't say bonds, I'd say interactions. :smile:
Hey guys, is this a wise decision? At the moment because I have so much content left- I don't think it's best to do any past papers at the moment. If I am lucky, maybe I will try the 2014 paper but since I am basically trying to learn the whole of Chem and Physics- I am planning just to go over the book, the specification and it's questions without any past papers.
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Original post by Feraligatr
Yep, charges are balanced :smile:


Sweeet :bigsmile:


Reduction of Water so splitting water into Hydrogen and Hydroxide ions

H2O --> H2 + OH-

(this is the equation at first - unbalanced)

I can't really explain it but you're trying to split water into hydrogen and hydroxide anions, so therefore you need to balance it now

If we multiply the water moles by 2 so 2H2O instead of H2O, you realise that they are 2 oxygen atoms and 4 hydrogen atoms.
Let's balance the remainder now. So let's leave the H2 for now but focus on the OH- though. Multiply by 2 so therefore

2H2O --> H2 + 2OH-
However the charges aren’t balanced L
Add 2 electrons to the reactant to balance the charges on both sides. Therefore the equation becomes
2H2O +e- --> H2 + 2OH-

4 hydrogens on both sides, 2 oxygens on both sides. Charges are also balanced. :smile:


Ow right! I got the H2O --> H2 + OH- bit, but I don't know, just thought it looked wrong haha. So just balancing then, makes sense!


2H2O + Ca +2e- = H2 + 2OH- + Ca2+ 2e-
That’s the combined equation at first. Immediately you can cancel out the electrons so the equation becomes
2H2O + Ca +2e- = H2 + 2OH- + Ca2+ 2e-
2H2O + Ca = H2 + 2OH- + Ca2+
I’m pretty sure that the hydroxide anions will attract the calcium cations so the final equation becomes
2H2O + Ca = H2 + Ca(OH)2


Nice emojis :wink: and Ye that makes sense, I would have probably just left it as 2OH- and Ca2+ but of course they attract :blushing:


Na2O + H2O à 2NaOH + ½H2
Pretty much the same thing as previous. You should recall from Group 2 that dissolving a metal oxide in water produces a hydroxide and hydrogen. Balancing here is slightly different though.


Na2O + 2HCl = 2NaCl + H2O
Again, pretty much the same thing as Group 2 metals J


Idk, I thought maybe group 1 elements react differently? I know how the group 2 elements react but thought that Group 1 elements wouldn't react similarly due to their charge of +1?



I wouldn’t really say that about this case because you’re not given the values.
I’m not sure, but hopefully if I’m wrong, someone will correct me :colondollar:
The reaction (NO + O2) has a lower activation energy as it undergoes an alternative pathway which requires less energy.
It may be so since the CO bond is stronger than the bond in diatomic oxygen so less energy (hence a lower activation energy) is required.



Ugh Idk, I don't like that question haha. Had to read it like 100 times to understand it :tongue:
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Hiya :hugs:
Original post by Dinaa



Nice emojis :wink: and Ye that makes sense, I would have probably just left it as 2OH- and Ca2+ but of course they attract :blushing:


Idk, I thought maybe group 1 elements react differently? I know how the group 2 elements react but thought that Group 1 elements wouldn't react similarly due to their charge of +1?

Ugh Idk, I don't like that question haha. Had to read it like 100 times to understand it :tongue:


I decided to copy everything on Word and then answer it :tongue:

Nope, they pretty much react the same except Group 1 Carbonates (except Lithium) don't thermally decompse.

That definitely was a weird question, just asking, what paper did it come from?
I actually don't even know :redface:
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Original post by Feraligatr
I decided to copy everything on Word and then answer it :tongue:

Nope, they pretty much react the same except Group 1 Carbonates (except Lithium) don't thermally decompse.

That definitely was a weird question, just asking, what paper did it come from?


Ooh Okay, thanks for telling me haha :tongue:

ALSO, I STARED AT THAT HALOGENS TABLE ON CHEMREVISE FOR AGES LAST NIGHT AND I FINALLY UNDERSTOOD IT!! MAKES SENSEEEE :awesome:

And I don't really know. I'm doing past paper questions by topic. Sorry haha :tongue:



Go study, you silly bum :ahee:

I'm about to go do some SQUATS :bigsmile:
Original post by Dinaa
Ooh Okay, thanks for telling me haha :tongue:

ALSO, I STARED AT THAT HALOGENS TABLE ON CHEMREVISE FOR AGES LAST NIGHT AND I FINALLY UNDERSTOOD IT!! MAKES SENSEEEE :awesome:

And I don't really know. I'm doing past paper questions by topic. Sorry haha :tongue:


You're welcome :smile:

:lol: I told you so :tongue:

Oh I see, I've never come across a question like that and I've done quite a few past papers for Unit 2. I'm assuming its Section C right? (the extract and then loads of questions)
Edexcel :smile: How about you?
Good Luck with your exam too :smile:
Tbh, I do loads of past papers and look for I go wrong and how to improve and stuff. Really helps doing that :smile:
How about you?
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Original post by Feraligatr
You're welcome :smile:

:lol: I told you so :tongue:

Oh I see, I've never come across a question like that and I've done quite a few past papers for Unit 2. I'm assuming its Section C right? (the extract and then loads of questions)


Nope, Section B. I thought section C is only in the IAL papers? I really need to start doing past papers :erm:
Do you print them out? Or get given them? Or do you do it on paper and read from your laptop?

I have been using my ipad and paper to do past papers and it's just so.. ugh boring. I need to go print a load out, but my school printing budget is £0 :awesome:

So yeah, will just ask my teacher :blushing:
Yea, I just hope I can pass though. Everyone I know personally seem to be doing past papers- even those who are getting E grades like me who are not sure of the content.
Original post by Dinaa
Nope, Section B. I thought section C is only in the IAL papers? I really need to start doing past papers :erm:
Do you print them out? Or get given them? Or do you do it on paper and read from your laptop?

I have been using my ipad and paper to do past papers and it's just so.. ugh boring. I need to go print a load out, but my school printing budget is £0 :awesome:

So yeah, will just ask my teacher :blushing:


I see :tongue:
Yep, Section C is in Unit 2 GCE papers too :smile:

We were given loads of past papers for Chemistry but I haven't started using them since I want to use them for like actual exam practice under exam conditions :tongue:
I do print them out sometimes if I can otherwise I use the laptop and read off the past papers online.




Yep, exact same problem :redface:
Its those silly mistakes which cost you :frown:

That's really really tight for grade boundaries. I think Edexcel aren't even that tight :redface:
Original post by Feraligatr
I see :tongue:
Yep, Section C is in Unit 2 GCE papers too :smile:

We were given loads of past papers for Chemistry but I haven't started using them since I want to use them for like actual exam practice under exam conditions :tongue:
I do print them out sometimes if I can otherwise I use the laptop and read off the past papers online.




Yep, exact same problem :redface:
Its those silly mistakes which cost you :frown:

That's really really tight for grade boundaries. I think Edexcel aren't even that tight :redface:


dude Edexcel chem is a lot more challenging than ocr chem, no offence.
Original post by Dinaa
Nope, Section B. I thought section C is only in the IAL papers? I really need to start doing past papers :erm:
Do you print them out? Or get given them? Or do you do it on paper and read from your laptop?

I have been using my ipad and paper to do past papers and it's just so.. ugh boring. I need to go print a load out, but my school printing budget is £0 :awesome:

So yeah, will just ask my teacher :blushing:


You should definitely print them. I print them and I find it better because I can highlight and annotate the questions and it also gives me a measure of how much to write.

Also helps with organisation because I'm not good at filing away loose sheets of paper :tongue:
I get asked for them too, and its like... even if I decided to break the rules and tell you, that would only bring the grade boundaries up. It is literally in your interest not to tell them the questions or answers as it makes it harder for you.
I think exam boards differ quite a bit, like we learn about Born-Haber in AS, AQA touch that in A2 and OCR don't do Born-Haber at all I think.
I think we learn most of the things in Unit 1 (like Hess's Law and Organic Chem) that AQA students learn in Unit 2 so to an extent, exam boards are different (kinda)

Original post by frozo123
dude Edexcel chem is a lot more challenging than ocr chem, no offence.


I'm well aware of that but Edexcel grade boundaries are a lot less tight than OCR.
I'm a Edexcel student and I'm kinda aware that we learn things they don't learn in OCR or AQA
Original post by frozo123
dude Edexcel chem is a lot more challenging than ocr chem, no offence.


Everything is relative..
OCR and AQA students are lucky :tongue:

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