Advanced Higher Chemistry 2012-2013

Glasgow is pretty small to be fair haha, as is Scotland itself.
Polomint city buddy, full of roundabouts

Oh that it is!

Tell me about it >.> every time I turn a corner hahaha! The whirlies is a horrible roundabout aswell!


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lmao I can't believe you know the Whirlies!
I live literally a 4 minute drive from there

pm me your facebook. I can't send you any pm's as you've exceeded a storage limit

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Doing Wine Analysis for my investigation, not what I wanted but that hardly matters, it seems quite easy but dull

Hey, I am also doing a wine\spirits analysis. What are your methods? I am doing a simple gravimetric weighing and my second is a back titration with potassium dichromate.


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Um I can't really check just now, but I decolourise the red wine (stir with activated charcoal), titrate the wines (with phenylalanine as the indicator) with Sodium Hydroxide, Do a thin layer chromatography, then another titration with the wine,Sodium Hydroxide, starch, and sulphuric acid against iodine.

Sounds thrilling... There is a girl in my class who keeps drinking the whisky I use. Might add some extra pure ethanol to spice things up...

Hey guys I'm back with TSR I was doing some past papers on chemistry and I've got some questions that I'm not sure about. Can anyone help me with these questions? Answers are the bold ones

2011 Multiple Choice Questions:

5. The ratio of the ionic radii in sodium chloride is approximately 1:2, whereas in caesium chloride it is approximately 1:1. A compound XY contains X+ ions with a radius of 133pm and Y– ions with a radius of 220 pm. In a crystal of XY, how many Y– ions surround each X+ ion as its nearest neighbour?

A 1
B 2
C 6
D 8

Thanks!

Welcome back!

I can't help with the other 2, but for that one you have to identify the type of ionic lattice(the fact that it's a lattice eliminates A & B) the ion is, which tells you how many negative ions surrounds the positive one. You divide the ppm of the -ve ion by the +ve one, if the answer is closer to 2, it is a sodium chloride type lattice (the +ve ion is small, therefore less -ve ions can surround it.) so the answer is C.

20. In the presence of bright light, hydrogen and chlorine react explosively. One step in the reaction is shown below.

H2(g) + Cl(g) → HCl(g) + H(g)
The enthalpy change for this step can be
represented as the bond enthalpy of

A (H—H) + (Cl—Cl)
B (H—H) – (Cl—Cl)
C (H—H) + (H—Cl)
D (H—H) – (H—Cl).

23. Which of the following reactions would show the greatest decrease in entropy?

A H2(g) + F2(g) → 2HF(g)
B KNO3(s) → KNO2(s) + ½O2(g)
C CO3 2–(aq) + 2H+(aq) → H2O(l) + CO2(g)
D CO3^ 2– (aq) + CO2(g) + H2O(l) → 2HCO3^– (aq)

With this one you have to look at the bonds being broken and made: as hydrogen is present as H2, there's two hydrogen atoms which are bonded to each other so that bond has to be broken. Also, HCl is formed meaning hydrogen and chlorine have to bond as well. As bond breaking is endothermic it's +ve and the bond making in HCl is exothermic which is why it's -ve



Decreasing entropy means something is becoming more ordered, which could be something changing state or a decrease in the number of molecules for example. In D, there are three reactants and then only two products so it's becoming more ordered and so a decrease in entropy


I hope I made some sense; explaining isn't one of my strong points!

Decreasing entropy means something is becoming more ordered, which could be something changing state or a decrease in the number of molecules for example. In D, there are three reactants and then only two products so it's becoming more ordered and so a decrease in entropy


I hope I made some sense; explaining isn't one of my strong points!

Just done the 2002 Past paper without realising I only had the multiple choice answers.. it's a long shot, but does anyone happen to have a full marking scheme??

Did you find that paper online? Just that I can't seem to find any papers older than 2003


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I was wandering, how much emphasis do your teachers put on your arrows in mechanisms being very exact? I've been finding some differences between her teaching and the bright red book. Eg, she calls Halogenation, Bromination. During the Halogenation, she failed to mention that the nucleophillic Br- ion can only attack from the side opposite the other Br atom due to its side - she did the mechanism incorrectly according the the bright red book. I am not sure who to believe?!


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