OCR Chemistry A F325 Equilibria, Energetics and Elements Wed 13 June 2012
Chemistry exam discussion - share revision tips in preparation for GCSE, A Level and other chemistry exams and discuss how they went afterwards.
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Re: OCR Chemistry A F325 Equilibria, Energetics and Elements Wed 13 June 2012does anybody have the mark scheme for http://www.a-levelchemistry.co.uk/OC...resources.html
the transition elements hw part 1 and 2? and the link for the test paper and the markscheme? thanks. -
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Re: OCR Chemistry A F325 Equilibria, Energetics and Elements Wed 13 June 2012Sorry, when I quoted you earlier I thought this was a maths thread and you were talking about a maths question. Only just scrolled up(Original post by Dan12)
Has anyone done june 2010 paper and question 7b?
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Re: OCR Chemistry A F325 Equilibria, Energetics and Elements Wed 13 June 2012Don't find the conc in 250cm^3, go a step back and use the mass of H2O2 you found in 250cm^3 and then divide this by 25cm^3 to get the concentration of the undiluted solution.(Original post by Dan12)
I found the concentration of h202 in 250cm3 but what do you do after that?
The same mass of peroxide in 250cm^3 is in the original 25cm^3 since the student only added water.
I got an answer of 15.9gdm^-3. -
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Re: OCR Chemistry A F325 Equilibria, Energetics and Elements Wed 13 June 2012I've found this question dunno which year it is tho so dont have the mark scheme..wondered if anyone has!? if not please mention what you put for 7 marks
The complex [CoCl2(H2NCH2CH2NH2)2] shows 2 types of isiomerism. Use this to explain what you understand by the term stereoisomerism. Include diagrams to show both types of isomers...
It was worth 7 marks -
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Re: OCR Chemistry A F325 Equilibria, Energetics and Elements Wed 13 June 2012It was Jan 05 Transition Elements - paper and marking scheme attached(Original post by arvin_infinity)
I've found this question dunno which year it is tho so dont have the mark scheme..wondered if anyone has!? if not please mention what you put for 7 marks
The complex [CoCl2(H2NCH2CH2NH2)2] shows 2 types of isiomerism. Use this to explain what you understand by the term stereoisomerism. Include diagrams to show both types of isomers...
It was worth 7 marks
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Re: OCR Chemistry A F325 Equilibria, Energetics and Elements Wed 13 June 2012This would be my idea:(Original post by arvin_infinity)
I've found this question dunno which year it is tho so dont have the mark scheme..wondered if anyone has!? if not please mention what you put for 7 marks
The complex [CoCl2(H2NCH2CH2NH2)2] shows 2 types of isiomerism. Use this to explain what you understand by the term stereoisomerism. Include diagrams to show both types of isomers...
It was worth 7 marks
-Define stereoisomerism
-State the two types
-Draw diagrams of each (2-4 marks) -
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Re: OCR Chemistry A F325 Equilibria, Energetics and Elements Wed 13 June 2012Oh I've seen/done this question. I don't know which paper it is either as I got it as part of a revision pack from my teacher. I have the mark scheme though:(Original post by arvin_infinity)
I've found this question dunno which year it is tho so dont have the mark scheme..wondered if anyone has!? if not please mention what you put for 7 marks
The complex [CoCl2(H2NCH2CH2NH2)2] shows 2 types of isiomerism. Use this to explain what you understand by the term stereoisomerism. Include diagrams to show both types of isomers...
It was worth 7 marks
One mark for the definiton of stereoisomer
Two marks for drawing cis and trans isomers
Two marks for drawing both optical isomers (must be mirror images)
[all diagrams to show 3D arrangement]
One mark for saying 'Enantiomers/non superimposable mirror images'
And one mark for saying 'rotate plane polarised light in opposite direction by same number of degrees'
I still don't really understand the last point, can anyone shed some light on this?
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Re: OCR Chemistry A F325 Equilibria, Energetics and Elements Wed 13 June 2012Yh the MS is up there! scroll up!(Original post by Cath-ay)
Oh I've seen/done this question. I don't know which paper it is either as I got it as part of a revision pack from my teacher. I have the mark scheme though:
One mark for the definiton of stereoisomer
Two marks for drawing cis and trans isomers
Two marks for drawing both optical isomers (must be mirror images)
[all diagrams to show 3D arrangement]
One mark for saying 'Enantiomers/non superimposable mirror images'
And one mark for saying 'rotate plane polarised light in opposite direction by same number of degrees'
I still don't really understand the last point, can anyone shed some light on this?
So As for last point! basically imagine you draw two enantiomers
then you shone light through a solution containing each of those enantiomers
for one of those solution: the enantiomer rotate the plane polarised light in clockwise direction
other enantiomer rotate it in anti-clockwise direaction
if you had both same amount (same volume?) then there will be no effect on the plane polarised light!
MS reads:"same number of degree" which I guess is referring to clockwise/anti .. (quote me if am wrong)
Couldn't figure out how we got cis/trans from a octahedral structure???? -
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Re: OCR Chemistry A F325 Equilibria, Energetics and Elements Wed 13 June 2012yh you wouldn't get all the marks! not that I would :P(Original post by LifeIsGood)
This would be my idea:
-Define stereoisomerism
-State the two types
-Draw diagrams of each (2-4 marks)
Ok you officially own the google! it took you 2 mins to find it!!! impressed!
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Re: OCR Chemistry A F325 Equilibria, Energetics and Elements Wed 13 June 2012I already had the paper, just had to google which one it was :P(Original post by arvin_infinity)
Ok you officially own the google! it took you 2 mins to find it!!! impressed!
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Re: OCR Chemistry A F325 Equilibria, Energetics and Elements Wed 13 June 2012These were the files that were uploaded to the website before some of the links became broken on transition metals, they probably aren't identical to the ones uploaded now with missing links but I suspect they're very similar(Original post by Tyles)
does anybody have the mark scheme for http://www.a-levelchemistry.co.uk/OC...resources.html
the transition elements hw part 1 and 2? and the link for the test paper and the markscheme? thanks. -
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Re: OCR Chemistry A F325 Equilibria, Energetics and Elements Wed 13 June 2012Sorry for the double post but I also have made some booklets for the 3 main topics in the exam. However they may be a bit broad so if anyone wants me to make a booklet that is more specific to a certain topic then feel free to ask
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Re: OCR Chemistry A F325 Equilibria, Energetics and Elements Wed 13 June 2012Ahh yeah, she got to it first(Original post by arvin_infinity)
Yh the MS is up there! scroll up!
So As for last point! basically imagine you draw two enantiomers
then you shone light through a solution containing each of those enantiomers
for one of those solution: the enantiomer rotate the plane polarised light in clockwise direction
other enantiomer rotate it in anti-clockwise direaction
if you had both same amount (same volume?) then there will be no effect on the plane polarised light!
MS reads:"same number of degree" which I guess is referring to clockwise/anti .. (quote me if am wrong)
Couldn't figure out how we got cis/trans from a octahedral structure????
(I'm on my phone and had to dig out my copy lol)
Hmmm I kinda see what you mean! So 'same number of degrees' must refer to the fact that they are mirror images... Thank you
For cis trans, two of the ligands are bidentate, so you kinda have to put aside knowing that the structure is octahedral and treat each ligand as if the structure was square planar. I.e. one isomer has the Cl opposite each other, as with the ethane-1,2-diamine, and the other isomer, Cl's next to each other and ethane-1,2-diamine adjacent. Hopefully this clears it up a bit?!? -
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Re: OCR Chemistry A F325 Equilibria, Energetics and Elements Wed 13 June 2012Haha..yh better be quick next time :P(Original post by Cath-ay)
Ahh yeah, she got to it first (I'm on my phone and had to dig out my copy lol)
Hmmm I kinda see what you mean! So 'same number of degrees' must refer to the fact that they are mirror images... Thank you
For cis trans, two of the ligands are bidentate, so you kinda have to put aside knowing that the structure is octahedral and treat each ligand as if the structure was square planar. I.e. one isomer has the Cl opposite each other, as with the ethane-1,2-diamine, and the other isomer, Cl's next to each other and ethane-1,2-diamine adjacent. Hopefully this clears it up a bit?!?
Well, I am glad I saw this question cuz I was gonna go to the exam room thinking cis/trans is only possible of tetrahedral and suqare planar -
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Re: OCR Chemistry A F325 Equilibria, Energetics and Elements Wed 13 June 2012I thought I'd finally got this paper nailed. I've worked really hard on it with my teachers to make sure I knew what I was doing. And then I just did a past paper, not sure which, and suddenly I can't do half of it.(Original post by Patchey1000)
How's everyone revising for this? Death by past paper? Seems to be the best way with so much of the exam based on calculations
I hate EEE so much :P -
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Re: OCR Chemistry A F325 Equilibria, Energetics and Elements Wed 13 June 2012Probably the June '11 paper(Original post by pcorbett94)
I thought I'd finally got this paper nailed. I've worked really hard on it with my teachers to make sure I knew what I was doing. And then I just did a past paper, not sure which, and suddenly I can't do half of it.
I hate EEE so much :P
(I'm on my phone and had to dig out my copy lol)
