IAL Edexcel A2 Chemistry Unit 6 (Old syllabus) Watch

Presto
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#81
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#81
Is [Cr(H2O)6]3+ violet or green?
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Presto
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#82
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#82
What organic reactions do we need to know?
All of them?
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CuriosityYay
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#83
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(Original post by Presto)
Is [Cr(H2O)6]3+ violet or green?
My book says both.
But for the sake of examination stick to green
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Presto
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#84
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Thanks!
(Original post by CuriosityYay)
My book says both.
But for the sake of examination stick to green
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sickomode
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#85
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#85
its better to know all the organic synthetic routes
(Original post by Presto)
What organic reactions do we need to know?
All of them?
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JanaALEVEL
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Keka Ferdousi
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#87
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#87
Any prediction guys?
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Keka Ferdousi
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#88
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Better to write green
(Original post by Presto)
Is [Cr(H2O)6]3+ violet or green?
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CuriosityYay
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What year/session?
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CuriosityYay
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A

nitro groups are electron withdrawing so make the ring much less reactive than the original benzene ring because less electrons are available in the delocalised system so less susceptible to electrophiles/electrophilic attacks.
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slightly_edited
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#91
I know this name very well. Do you know me by any chance? slightly_edited used to be my Instagram account name.
(Original post by saphira_jade)
Then for NMR?]]]]]]]]]]]]]]
(Original post by saphira_jade)
We do
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Khazard
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(Original post by CuriosityYay)
The sign of a standard electrode potential indicates the polarity of the electrode relative to standard hydrogen electrode. This sign is fixed and doesn't change if the equation for the half-cell is reversed. Standard electrode potential is described as being a 'sign invariant quantity'.
This site says otherwise https://www.chem.wisc.edu/deptfiles/...tial/18_52.htm
and talks all about "reversing equations to that yields highest positive net emf of the cell" and " Remember that when one reverses a reaction, the sign of Eº (+ or –) for that reaction is also reversed."
and so does this site https://www.cliffsnotes.com/study-gu...rode-potential
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Khazard
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(Original post by Presto)
Is [Cr(H2O)6]3+ violet or green?
Solutions containing Cr2+ are violet/blue, but Cr3+ are green.
If you look up January 2018 question 1, you'll see the difference.
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CuriosityYay
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(Original post by Khazard)
This site says otherwise https://www.chem.wisc.edu/deptfiles/...tial/18_52.htm
and talks all about "reversing equations to that yields highest positive net emf of the cell" and " Remember that when one reverses a reaction, the sign of Eº (+ or –) for that reaction is also reversed."
and so does this site https://www.cliffsnotes.com/study-gu...rode-potential
My book explicitly states:

The sign of a standard electrode potential indicates the polarity of the electrode relative to standard hydrogen electrode. This sign is fixed and doesn't change if the equation for the half-cell is reversed, as sometimes stated elsewhere. Standard electrode potential is described as being a 'sign invariant quantity'.

Moreover, in the question, you subtract without changing the sign of the electrode potential.
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JanaALEVEL
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(Original post by CuriosityYay)
A

nitro groups are electron withdrawing so make the ring much less reactive than the original benzene ring because less electrons are available in the delocalised system so less susceptible to electrophiles/electrophilic attacks.
If the nitro group is withdrawing and makes nitrobenzene less susceptible to attack then why would further nitration occur ?
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CuriosityYay
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(Original post by JanaALEVEL)
If the nitro group is withdrawing and makes nitrobenzene less susceptible to attack then why would further nitration occur ?
It is less susceptible to electrophiles so at low temperatures only single substitution occurs and it stays as nitrobenzene but at higher temperatures double substitution occurs.
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Faiza_shuja
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Does anyone have any predictions of what can come? I'm really scared unit 6 is unpredictable.
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JacobBob
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(Original post by CuriosityYay)
My book explicitly states:

The sign of a standard electrode potential indicates the polarity of the electrode relative to standard hydrogen electrode. This sign is fixed and doesn't change if the equation for the half-cell is reversed, as sometimes stated elsewhere. Standard electrode potential is described as being a 'sign invariant quantity'.

Moreover, in the question, you subtract without changing the sign of the electrode potential.
Did you take unit 4 in jan ?
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CuriosityYay
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(Original post by JacobBob)
Did you take unit 4 in jan ?
No, I am doing all 6 papers this semester.
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carolinaaa
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Hey guys any predictions ? Tbh anything could be in it
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