AS Chemistry- helping each other out!

Same

Im Doing aqa as well unit 1 is okay unit 2 looks hard

E.g KNO3 This is potassium nitrate, but in order to be complete we need to get systematic name we need the oxidation of nitrogen. We know that K forms +1 ions, so charge on the nitrate ion must be (-2*3) -6. The book says that that know the oxidation number of the overall ion is -1. How do we know it's -1 I would have assumed it would have been 0. Can someone please help me out, I'm quite confused.

E.g KNO3 This is potassium nitrate, but in order to be complete we need to get systematic name we need the oxidation of nitrogen. We know that K forms +1 ions, so charge on the nitrate ion must be (-2*3) -6. The book says that that know the oxidation number of the overall ion is -1. How do we know it's -1 I would have assumed it would have been 0. Can someone please help me out, I'm quite confused.

E.g KNO3
Also in Cu2O How am I supposed to know that when we find the systematic name of it we need to find the oxidation of Copper in this example. Why are we not finding the oxidation state of oxygen?

Oxygen nearly never changes (you can say it's -2 pretty much all the time- it certainly doesn't change enough that it warrants an oxidation state in its systematic name) Copper is a transition metal, meaning its oxidation state changes loads. Generally if you have a transition metal, that's the most important thing to give the oxidation number of.


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The Avogadro Constant (N_A) is number of particles of a substance (atoms, molecules, ions) in one mole of the substance.

So, first, you need to work out how many moles of water there are, and then multiply that by N_A for the number of molecules of water (because you used the number of moles of H₂O, which is a molecule, you'll get the number of molecules out).

Then have a think about how you get from molecules to atoms.

People in the year above said they did not have much time to revise unit 2. As a result, most people did better in unit 1 but really badly in unit 2. We did a bit of unit 2 before the holidays and it was undoubtedly difficult to understand. Also the ISAs are horrible with their monstrous grade boundaries. Which the the result of some schools cheating on them.

Hiya, I'm doing OCR B

Yeah I knowing heard unit 2 is quite difficult to understand I might look over it . I'm doing empa's which are simmilar to Isa's but they are externally marked so lower grade boundaries but are difficult as you get o help From teachers have you done any praticals

Hello AS Chemistry TSRians!

I thought it would be a good idea to make a thread, where students doing AS Chemistry, post/ask questions, and we could all help each other out?

Teaching another person, also helps you become more confident and you both develop a better understanding. I know there is an A-level chat thread already, but this should be for learning!

There is no such thing as a silly question, so ask away and hopefully, you'll find someone who can help you

I shall also make a list of the Chemistry students, and what exam board they're all on! So please post what exam board you are on, if you are in!

List of the students doing Chemistry!


Lovely helpers!



I apologize if I've missed anyone out, got the list from Current year 12 list! (Lazy i know)

P.S- If you don't want to, okay, you are not obliged to do so! But please, no rude/offensive comments

Can somebody please explain to me about reacting an acid and a base.
So the general formula is
Acid + base --> salt + water

E.g HCl with calcium oxide as the base
So hydrochloric acid + calcium oxide --> calcium chloride + water
Same as - 2HCl + CaO --> CaCl2 + H2O

Does the HCl release it's H+ ions and the H+ cannot be in water as H+ so it has to bond with water to, H3O+. Then We have the Cl and the Calcium which bond together and form CaCl2... is this correct?

Yeah It's correct but the formula for water is H2O

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I know :P but I thought H2O + H+ --> H3O+ ? Unless I am mistaken