Today's AQA CHEM 5/6...

imasillynarb

What about the Elements of the period 3 Oxides?

I got: Na, P, Si

Anyone else?

damn......i'm not even crap at chem, but i totally messed up unit5, cos i only had last nite 2 revise.......and i knew it was either Na or Mg, but decided to put Mg......what an idiot. i got P right tho......got Si wrong, chose Al. lol cos i kept thinking how could SiO2 b a crystal

Reply 41

Resonance

For the Acidity of Fe3+ question:

When it was FeCl3 and you dissolve it, the Fe3+ ion accepts the lone pairs off the water molecules that become ligands, so it is in that case an Electron Pair Acceptor, a Lewis Acid.

When it is [Fe(H2O)6]3+, since it is a very highly charged metal it drags electron density away from an oxygen atom, which in turn drag it away from the hydrogens connected to it, and then a water can remove one of the hydrogens, forming the H3O+ cation.
So in that case it acts as a Proton Donor, which is a Bronsted-Lowry Acid.

Reply 42

Barny

17

wonkey

damn......i'm not even crap at chem, but i totally messed up unit5, cos i only had last nite 2 revise.......and i knew it was either Na or Mg, but decided to put Mg......what an idiot. i got P right tho......got Si wrong, chose Al. lol cos i kept thinking how could SiO2 b a crystal

Im crap at chem and only had last night to revise, whats your point? :rolleyes:

Reply 43

babylon

imasillynarb

Im crap at chem and only had last night to revise, whats your point? :rolleyes:

well did u do badly?

Reply 44

Barny

17

Oh yeh, when you had to write the Kp expression, did everyone just put

kp = (pZ)(pW)/(pY)(pX)

Or whatever it was?

Reply 45

Sapphira

it had to be to the power of the number of moles of each substance

Reply 46

Barny

17

wonkey

well did u do badly?

very

Reply 47

Barny

17

Sapphira

it had to be to the power of the number of moles of each substance

I dont think it does, the Kp is TO DO WITH partial pressure, which is the mole fraction x total pressure. Therefore number of moles comes into the mole fraction...which is represented by the partial pressure, which is just (pX) or whatever it was?

Reply 48

Sapphira

nope, its def to the power...just looked in text book

Reply 49

zazy

1

imasillynarb

I dont think it does, the Kp is TO DO WITH partial pressure, which is the mole fraction x total pressure. Therefore number of moles comes into the mole fraction...which is represented by the partial pressure, which is just (pX) or whatever it was?