AS Chemistry- helping each other out!
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Original post by C0balt
Well what group is S in? Group 6. They usually form 2- ions when reacted with metals. And it says iron (II) sulfide which means that the oxidation number for iron is +2. So it's 2 to -2 already and the "charge" balances so it's just FeS
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Original post by Zer0.
Use your knowledge of oxidation states - Iron(II)Sulfide: We're aware that Iron, in this instance, will have an oxidation state of +2, we're also aware of the fact that Sulfur will always have an oxidation state of -2 (Group 6), so in order to equate the oxidation state value to 0 we'll require one atom of Iron and one atom of Sulfur, thus creating Iron Sulfide: FeS!
Ahhhhhh I get it now thank you !!!!!!!
hey I'm a bit confused on this question- would be grateful for any help
so I get that the green colour disappears when the NaOH is added because it reacts with either acid on the right and the equlibrium has to shift to the right to restore the acid. My question is why doesn't the NaOH react with the chlorine? In this case the equilibrium would shift the other way ....sorry if this is confusing!
if anyone could help me with this I'd be really grateful - it's not like the other Hess' cycles
Original post by VetVikki
if anyone could help me with this I'd be really grateful - it's not like the other Hess' cycles
The way I teach this to my students is to get them to set up the Hess cycle and then say that
anti-clockwise arrows = clockwise arrows
So;
+ 963 + ΔH = -432 + (-75)
ΔH = -1470
for ocr f322
what do you need to know for these points on spec
- describe benefits of developing chemical processes with high atom economy in terms of fewer waste products
- explain a reaction may have a high % yield but a low atom economy
thanks
what do you need to know for these points on spec
- describe benefits of developing chemical processes with high atom economy in terms of fewer waste products
- explain a reaction may have a high % yield but a low atom economy
thanks
Wat
Original post by hibaj
for ocr f322
what do you need to know for these points on spec
- describe benefits of developing chemical processes with high atom economy in terms of fewer waste products
- explain a reaction may have a high % yield but a low atom economy
thanks
what do you need to know for these points on spec
- describe benefits of developing chemical processes with high atom economy in terms of fewer waste products
- explain a reaction may have a high % yield but a low atom economy
thanks
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For spec,recognise which bonds vibrate,like OH in water,C=O in co2 and CH in methane.
Learn how to interprete what functional groups are in a compound from the spectrum (IR)
Learn about the fragments (mass spec) which ones can come from a compound (use molar mass) and.that they are unique.
Learn about applications of both.
Chemical processes with high atom economy means less waste products are produced,so it is.more sustainable, more desired product, cheaper as less money spent disposing of waste products and separating them from the desired product.
High percentage yield means most of the reactants are converted into the products, but it can have. Alow atom economy as most of the products could be the waste product and not the desired product.
Hope this helps
.Original post by Dinaa
Wat
Wat
Wow, my over board studying of green chemistry might actually pay off. I'm going to attempt this.
*ahem*
Initiation:
CCL2F2 ----> CClF2• + Cl•
Propagation:
Cl• + O3 ----> ClO• + O2
ClO• + O3 ----> 2O2 + Cl•
Termination:
They'll probably accept any two free radicals combining.
ClO• + Cl• ----> Cl2O
It's a serious issue because the free radical regenerates and continues to break down ozone into oxygen depleting the amount of ozone we have. Edit: Due to the depletion, more UV rays enter and causes skin cancer and other bad things.
So overall we get something like:
2O3 --> 3O2
Note: still kind of iffy about the propagation steps so please do check them with a mark scheme or something.
(edited 8 years ago)
Original post by TeachChemistry
The way I teach this to my students is to get them to set up the Hess cycle and then say that
anti-clockwise arrows = clockwise arrows
So;
+ 963 + ΔH = -432 + (-75)
ΔH = -1470
anti-clockwise arrows = clockwise arrows
So;
+ 963 + ΔH = -432 + (-75)
ΔH = -1470
Thankyou for replying
What do you mean when you say "anti-clockwise arrows = clockwise arrows" and with the arrow along the bottom for the reaction equation, is that a + or - sign, that's where I'm confused 
Original post by thymolphthalein
.
i like your name
Original post by C0balt
i like your name
I like yours too.
Phenolphthalein was taken.
Original post by thymolphthalein
I like yours too.
Phenolphthalein was taken.
Phenolphthalein was taken.
Cobalt was taken lolnow I know how to spell phenolphthalein thanks to your name
Help with redox ewuation for SO4 2- ---> SO2
Original post by Dinaa
Help with redox ewuation for SO4 2- ---> SO2
S goes from 6 to 2 (it is reduced) - hope this helps
Original post by VetVikki
Thankyou for replying What do you mean when you say "anti-clockwise arrows = clockwise arrows" and with the arrow along the bottom for the reaction equation, is that a + or - sign, that's where I'm confused
What do you mean when you say "anti-clockwise arrows = clockwise arrows" and with the arrow along the bottom for the reaction equation, is that a + or - sign, that's where I'm confused See below.
Hi I'm doing OCR A Chemistry. How is everyone feeling for the F322 paper?
Original post by Dinaa
Help with redox ewuation for SO4 2- ---> SO2
Does it mention whether it's in acidic medium or alkaline medium?
In acidic medium:
SO42- + 4H+ + 2e- ------> SO2 + 2H2O
How do you tell if a molecule is polar or not?
Original post by C0balt Cobalt was taken lol
now I know how to spell phenolphthalein thanks to your name
Cobalt was taken lolnow I know how to spell phenolphthalein thanks to your name
I did actually see a mark scheme that specifically said to reject phenolphthalein if you spelt it wrong lol
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Original post by samb1234
I did actually see a mark scheme that specifically said to reject phenolphthalein if you spelt it wrong lol
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yeah usually they accept recognisable phonetic spelling but once they felt like rejecting lol
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