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Aqa chem 4/ chem 5 june 2016 thread

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Jenza
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Original post by shiney101
Does anyone know whether they asked for the shape of the complex?


I want to know this too because i forgot to draw the complex!
Original post by DDan123
I just remembered that I drew the complex with the ethane-1,2-diamine ligands in pencil. Is that okay :/


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As long as it was standard HB pencil then yeah
Original post by EverydayHell
For Q in the chromium chemistry I said NH3 not in excess and the gas produced was NH4+, do you think this could still be right?


Nh4+ isn't a gas.
Can someone clarify how many marks I would get for using; SO2+ 0.5O2 --> SO3 , in each question involving;
Enthalpy: My answer was half the correct (0) marks/2
Entropy: Since using the SO2+ 0.5O2 --> SO3 equation my entropy was also half (0 or 2 ? as follow through of error in eq) marks/2
Gibbs: My answer was calculated using the half the correct values (follow through based on previous answers)/3


Am I awarded 3/7 or 5/7 ?
For the emf graph, I drew a 'straight' line free-hand because I didn't have a ruler... will I lose the marks lol? It was a pretty shakey line..
Original post by Jenza
I want to know this too because i forgot to draw the complex!


Original post by shiney101
Does anyone know whether they asked for the shape of the complex?


Yeah, they asked to draw the complex, I doubt it would be more than two marks though...
Yeah, so why did increasing pressure affect the oxygen half equation if they weren't all gaseous?
,

Original post by Sniperdon227
Can someone clarify how many marks I would get for using; SO2+ 0.5O2 --> SO3 , in each question involving;
Enthalpy: My answer was half the correct (0) marks/2
Entropy: Since using the SO2+ 0.5O2 --> SO3 equation my entropy was also half (0 or 2 ? as follow through of error in eq) marks/2
Gibbs: My answer was calculated using the half the correct values (follow through based on previous answers)/3


Am I awarded 3/7 or 5/7 ?


I made the exact same mistake, would we not get 3/3 for the gibbs if we still did the right equation?
Original post by DDan123
I just remembered that I drew the complex with the ethane-1,2-diamine ligands in pencil. Is that okay :/


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Should be as long as it's hb or b.
Original post by cookiemonster15
,



I made the exact same mistake, would we not get 3/3 for the gibbs if we still did the right equation?


If you halved them both, Gibbs would take exactly the same value - it is only a measure of feasibility and doesn't depend on the number of species on either side.
Original post by Jenza
I want to know this too because i forgot to draw the complex!


But i mean like the name of the shape ie: octahedral?
Original post by cookiemonster15
Should be as long as it's hb or b.


Ahh yh it was hb, I've already dropped enough silly marks really can't afford anymore 😂


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Original post by ChronicBoredom
For the emf graph, I drew a 'straight' line free-hand because I didn't have a ruler... will I lose the marks lol? It was a pretty shakey line..


Not unless your examiner is a padantic *******
Guys, would I get 'ethanol' as a suitable reagent for reducing Cr3+ to Cr2+? (I put Cr2+ is blue, so that's one mark at least!).
Original post by zombaldia
Not unless your examiner is a padantic *******


This is AQA we're talking about...
Original post by Jenza
I want to know this too because i forgot to draw the complex!


It did NOT say to name the shape.
Original post by Aethrell
Yeah, so why did increasing pressure affect the oxygen half equation if they weren't all gaseous?


Also, wouldn't increasing the surface area of the platinum electrodes speed up both reactions lead to a faster transfer of electrons and give a higher emf?
Original post by Cadherin
Guys, would I get 'ethanol' as a suitable reagent for reducing Cr3+ to Cr2+? (I put Cr2+ is blue, so that's one mark at least!).


Only thing I've heard of is zn/excess hcl which is what I put
Original post by Aethrell
Also, wouldn't increasing the surface area of the platinum electrodes speed up both reactions lead to a faster transfer of electrons and give a higher emf?


As you said... it speads up both reactions. So has no effect overall. Could be wrong though
Original post by Cadherin
This is AQA we're talking about...


Jokes aside, I don't think they'll penalise you for not drawing a straight line. It's the logic behind it that matters and if you've displayed the correct understanding then it should be correct. That's what I believe anyway

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