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***2013 LC Chemistry Before/After***
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RabbitHearted wrote: »Can someone state Pauli's Exclusion Principle for me? It's not in my book and we never mentioned it?
Also, earlier in the thread a couple of you mentioned not being able to do the ethanoic acid/ethanal exp.s.. you should come to our class we did all of them, including ones that have been completly taken off the course ie ones that were on the old course and the prep room is full of banned chemicals because apparently there only accumatively carcinogenic so were grand
Also the ethanal exp was brilliant, we set the floor on fire with the most amazing green blue flames. Safety first..
Pauli exclusion principle states no more than 2 electrons may occupy an orbital and must be of opposite spin. so only a max of two can be in it and when drawing the elctrons, they must be the opposite way around.
https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcQDFjsK7IJVR3rA6quZ5VR99vwSelGVIlHibBtBMZHx5dayT2w-9Q
you see the way the thing is the opposite way around, it means opposite spin 0 -
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That's not what i meant when i said no change I know pressure has an effect on the equilibrium, but anyway it would decrease it caus Pcl5 is on the bottom for Kc remember
Sorry.
Okay so if the number on the bottom increses, Kc deccrease!
thanks
****, we're wrong. No effect on Kc as it is only temp dependent. The pressure only affects equilibrium. I checked marking scheme! 0 -
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outnumbered wrote: »Sorry.
Okay so if the number on the bottom increses, Kc deccrease! thanks
****, we're wrong. No effect on Kc as it is only temp dependent. The pressure only affects equilibrium. I checked marking scheme!
But I just checked the sample answer on e-xamit and it says it decreases.. Yet i remember my teacher saying what you've just said.. Argh this is so annoying, this is the one answer that seems to always change!0 -
Think they gave three marks for the normal le chatelier principle approach out of six.outnumbered wrote: »When there is a system in equilibrium and it asks what change of Kc would an increase in pressure have:
I know you count no of moles on boths sides la la la .
But what change of Kc occurs. Say the reactant on the right increase in concentration, what effect does this have on Kc. For an example refer to 201o q7 e
No effect on Kc because Kc is given at a constant temperature and set at equilibrium. If I'm not mistaken, there is only one Kc value per reaction equation and it applies only at equilibrium. In cases of concentration or pressure changes, the system will readjust itself to satisfy Kc or Kp value.outnumbered wrote: »No there is a change. It goes from high no of moles to low no of moles. so an increase on Pcl5 but ehat effect does the increase of pcl5 have on Kc?
But, in case of temperature changes, the value of Kc or Kp changes. Whenever equilibrium shifts to right by the effect of temperature change, Kc and Kp will be greater and whenever equilibrium shifts to left by the effect of temperature change, Kc and Kp will be smaller.
You were right the first timeWait i change my mind - the pressure would affect it 0 -
Think they gave three marks for the normal le chatelier principle approach out of six.
No effect on Kc because Kc is given at a constant temperature and set at equilibrium. If I'm not mistaken, there is only one Kc value per reaction equation and it applies only at equilibrium. In cases of concentration or pressure changes, the system will readjust itself to satisfy Kc or Kp value.
But, in case of temperature changes, the value of Kc or Kp changes. Whenever equilibrium shifts to right by the effect of temperature change, Kc and Kp will be greater and whenever equilibrium shifts to left by the effect of temperature change, Kc and Kp will be smaller.
You were right the first time
Not according to e-xamit
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Then e-xamit's wrongNot according to e-xamit no joke!
http://pdst.ie/sites/default/files/2010hlms_0.pdf
Q7 (e)
It is right e-xamit has been wrong many a time before. 0 -
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I think that's the right approach. Think its safe enough to leave out the benzoic acid question and the other 2 that came up last year in the experiments?Monsieur Folie wrote: »What's everyone prioritising for their last minute stuff? I've gone over most of the chapters at this stage, so I'll probably prioritise my organic chemistry and all the experiments the night before (and morning of), with a quick glance over anything else that's unfamiliar to reassure myself.
Organic chemical reactions is a must too! 0 -
Yeah, I wouldn't rely on e-xamit. Always go for the official marking scheme to be sure of yourself!I think that's the right approach. Think its safe enough to leave out the benzoic acid question and the other 2 that came up last year in the experiments?
Organic chemical reactions is a must too!
Organic chemical reactions must be the one part of the course I've never learned off. I'll get on it though, lots of time the night before/morning of to make sure it stays fresh! I don't see them repeating an experiment, but I will do every single one just to cover myself, since they are a guaranteed three questions! 0 -
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YoursSincerely wrote: »Me too, I have physics and accounting tomorrow, chem on tues and applied maths, I am going to get very little sleep this week
JESUS CHRIST you frightened me sooooooo Bad!!!!!!!!!
Tomorrow is sunday..... Phewwww0 -
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MarieCurie22 wrote: »Hey at least its better than thinking its friday...and spending half the day in bed now ive so much to do in 1.5 days!!!
Haha by the looks of things, I think you'll do juuuuuuust fine! :P0 -
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Does anyone else have 4 subjects left? I have this, physics, app maths and spanish and i feel so overwhelmed
Phys, Chem, Music, Applied Maths for me. Tough week, though once physics and chem are outta the way it's just a case of not failing the other two, since I hopefully won't need to count them. :P0 -
Monsieur Folie wrote: »Phys, Chem, Music, Applied Maths for me. Tough week, though once physics and chem are outta the way it's just a case of not failing the other two, since I hopefully won't need to count them. :P
Ive 3 Physics, chemistry and applied maths which im so not looking forward to 0 -
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outnumbered wrote: »From your posts you're clearly brilliant at chemistry
Thanks
although physics Im not so hot at so got that monday....Anyone here actually interested in doing chem in college? Or are you all MED? 0 -
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MarieCurie22 wrote: »Ive 3 Physics, chemistry and applied maths which im so not looking forward to
There is a very high probability I'm going to fail applied maths, which is a shame. I've only looked at 4 Q's in any sort of detail, having only started it after the mocks. I'm annoyed about that, I love the subject so much & I can tell that if I'd done it since 5th year it would be my favourite subject, but I've just no time for it 0
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