OCR Chemistry A F325 Equilibria, Energetics and Elements Wed 13 June 2012

h2o2 + 2I- + 2H+ gives I2 + 2H2O

cool

give 2 ways 2 H2 can be obtained.

electrolysis of water
reacting methane with steam

Why is there an exception in the electron configuration of Chromium and copper?

Why is there an exception in the electron configuration of Chromium and copper?

Reduced electron repulsions means its more stable to have one electron in 4s orbital



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Reduced electron repulsions means its more stable to have one electron in 4s orbital



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The obvious explanation is that chromium takes up this structure because separating the electrons minimises the repulsions between them - otherwise it would take up some quite different structure.
But you only have to look at the electronic configuration of tungsten (W) to see that this apparently simple explanation doesn't always work.

hi mate how are you shall we continue asking questions

Im very very very stressed out for my physics exam Monday. Trying to meet my Cambridge offer is making me ill! So much pressure, and my parents assume I'm going to do well - so much pressure .


Lying in bed wide awake :L


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trust me mate i am in the same position as you it is soo stressing i am killing my self its hard! is your first exam on monday chem is on wednesday
so yes or no you want to revise?

Im very very very stressed out for my physics exam Monday. Trying to meet my Cambridge offer is making me ill! So much pressure, and my parents assume I'm going to do well - so much pressure .


Lying in bed wide awake :L


This was posted from The Student Room's iPhone/iPad App

Im very very very stressed out for my physics exam Monday. Trying to meet my Cambridge offer is making me ill! So much pressure, and my parents assume I'm going to do well - so much pressure .


Lying in bed wide awake :L


This was posted from The Student Room's iPhone/iPad App

Definite no - just trying to tire my eyes so I can get some kip! I've had stats last month - but I've just burnt out and don't care. Just going to see what happens!


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G495? I feel you bro. I've focused all my revision on physics and haven't done anywhere near enough for chemistry

That's exactly what I've done! I've spent so much time working for my subjects, but not actually revised? It's weird, I've not gone partying at weekends, cut down on sport and Xbox - but just haven't taken in the facts!


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I feel like I've reached saturation point with regards to revision... like, I read things, but it doesn't make a difference because there will inevitably be a horrible unpredictable question that's not in the syllabus that screws you over. F325 is notorious for those questions.

I feel like I've reached saturation point with regards to revision... like, I read things, but it doesn't make a difference because there will inevitably be a horrible unpredictable question that's not in the syllabus that screws you over. F325 is notorious for those questions.

Guys do you know where I can find more practice questions?