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AS Chemistry- helping each other out!

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Original post by Dinaa
Yep, probably the worst :sad:




I have a question again! :h:

Na2O + H2O ---> ?

Na20 + HCl ----> ?

And If the light emitted from excited Caesium atoms is passed through a spectrometer, what would you expect to see?

Thanks :smile:


Oh yeah I had forgotten there were some simple ones in c2 as I've mainly been doing c3 recently where there are a huge number of trig identities. In answer to your question you would see black lines on the spectrum. Do you do physics?

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Original post by Dinaa
Thank you! And yeah Chemguide is great. Feel like it gives me what the exams wants lol :colondollar:



I got a B rofl for the Unit 2 paper, but idrc because it was super hard anyway. Andd Idk about UMS? Teacher just gave us the grade lol.

For the Unit 1 paper I got an A and raw marks: 68/70 :smile:

Maths is good (still need to do trigonometric identities for C2 though! and I don't really look at S1 lol), Chemistry is good, Biology is boring but have notes and stuff, just need to practice. Psychology is gay but I've started revising for it :smile:

Wby?




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Biology,We did a mock,I'm waiting for the results.My revision for the exams is going well,I have all the content knowledge,just doing tonnes of questions now.

I did the empa,my fingers are crossed for an A.Im hoping for low grade boundaries.
Chemistry-ISA worrying me.Resitting a few of them.Unit 1 is going fine.Unit 2 is my big worry.I'm revising loads for it.

Maths -C1, I'm doing well and Aiming for 100 percent.Trig and integrating under curves is my only worry for c2.S1 is a nightmare.Im only starting to revise seriously for it now.
Physics-feel like I messed up my coursework.However,I am doing well the past papers.
http://gyazo.com/958dda1c67f454af75fb1cd94d855fe1

wtf is this?
Original post by BBeyond


Was this in physics or chemistry? Btw the answer is an arrow from the bottom to the top

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Original post by samb1234
Was this in physics or chemistry? Btw the answer is an arrow from the bottom to the top

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chemistry, but why?
Original post by BBeyond
chemistry, but why?


That is quite sneaky as really this is a physics question. That diagram is called an electronic energy level diagram. Basically the way the diagram works is that at n=1 the attraction is the strongest and at n=infinity there is no attraction. Therefore if you want to move the electron from n =1 to n=infinity you have to provide it with that much energy.

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Original post by samb1234
That is quite sneaky as really this is a physics question. That diagram is called an electronic energy level diagram. Basically the way the diagram works is that at n=1 the attraction is the strongest and at n=infinity there is no attraction. Therefore if you want to move the electron from n =1 to n=infinity you have to provide it with that much energy.

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oh that makes sense cheers, so if it was electron affinity it would be from infinity to n=1?
Original post by samb1234
Was this in physics or chemistry? Btw the answer is an arrow from the bottom to the top

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Wow,cruel exam board.Energy levels is a physics concept,I think that's is what is called orbitals in chemistry.
Original post by BBeyond
oh that makes sense cheers, so if it was electron affinity it would be from infinity to n=1?


For hydrogen yes. As far as I'm aware you wouldn't need to know what it was for other elements as I don't think it would necessarily be from infinity to n=1

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Original post by samb1234
That is quite sneaky as really this is a physics question. That diagram is called an electronic energy level diagram. Basically the way the diagram works is that at n=1 the attraction is the strongest and at n=infinity there is no attraction. Therefore if you want to move the electron from n =1 to n=infinity you have to provide it with that much energy.

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To be fair,they do it in chemistry but in a sneaky way.Take a closer look at the diagram from my chemistry book.
1430580969439.jpg38.9KB
Original post by samb1234
That is quite sneaky as really this is a physics question. That diagram is called an electronic energy level diagram. Basically the way the diagram works is that at n=1 the attraction is the strongest and at n=infinity there is no attraction. Therefore if you want to move the electron from n =1 to n=infinity you have to provide it with that much energy.

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I'm upset we don't do orbitals in physics.They are the quantum mechanical version of the bohr model.
Original post by BBeyond
oh that makes sense cheers, so if it was electron affinity it would be from infinity to n=1?


Btw if you didn't know these diagrams also explain why you get black lines on an emission spectra. I won't go into much detail but the wavelength, and hence colour of a photon (light 'particle') is related to its energy. When an electron loses energy (ie moves down 1 or more levels) a photon of the difference in energy is released. Because the levels are discrete, there are some energies the emitted photon can never have so some wavelengths you will never get

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Original post by Dinaa
Banned lol =)

HOW HAVE YOU BEEENN!!!!!? stranger :erm: :tongue:


Why were you banned lol
stranger's been good yup :ahee:


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Original post by Kadak
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Wow,cruel exam board.Energy levels is a physics concept,I think that's is what is called orbitals in chemistry.


Energy level is called energy level or shell in chemistry lol
Orbital is a region in which there is a high probability of finding one or two electrons.

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Original post by C0balt
Energy level is called energy level or shell in chemistry lol
Orbital is a region in which there is a high probability of finding one or two electrons.

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:colondollar:.
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Avatar for Dinaa
Dinaa
OP
17
Original post by samb1234
Oh yeah I had forgotten there were some simple ones in c2 as I've mainly been doing c3 recently where there are a huge number of trig identities. In answer to your question you would see black lines on the spectrum. Do you do physics?

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Oh dear :sad:

I hate Trig identities so much, ugh C3 has more :cry2:


Also, wth lol how am I suppose to know that? Nope I don't :colondollar:
Hey guys,
I'm confused..
how come in enthalpy change questions, they sometimes give you enthalpy of formation data in a table, and then ask you to calculate the enthalpy of combustion?

I don't understand..what do I do?
Original post by wednesday_adams
Hey guys,
I'm confused..
how come in enthalpy change questions, they sometimes give you enthalpy of formation data in a table, and then ask you to calculate the enthalpy of combustion?

I don't understand..what do I do?

Combustion is
Sum of enthalpy of reactants - sum of enthalpy of products


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Original post by Dinaa
Oh dear :sad:

I hate Trig identities so much, ugh C3 has more :cry2:


Also, wth lol how am I suppose to know that? Nope I don't :colondollar:


Yep c3 has too much trig what with double angle formulas, 3 new trig things cot sec cosec etc etc. Basically all you need to know is that when you heat something the electrons will gain energy and will move to a higher energy level. When they lose energy and move back down, they emit a photon (light particle) with as much energy as they have just lost. The wavelength (and hence colour) of a photon is related to its energy. These energy levels are discrete so only photons of certain energies and hence wavelength can be emitted, meaning that you get black lines on the spectrum where nothing was emitted

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Avatar for Dinaa
Dinaa
OP
17
Hai der :ahee:

The effect of light on Silver Nitrates:

The precipitates, except AgI(s), darken in sunlight forming silver. This reaction is used in photography to form the dark bits on photographic film.

OK but questions:

WHY do they darken in sunlight?
Is there an equation for this?
Why can't AgI(s) darken?

curious :mmm:

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