Career in politics anyone?

In the reshuffle of the ministers of the Welsh Government announced today. There was a significant coincidence in amongst all the other flannel. The new Minister for Education and Skills is an ex-Chemistry teacher (Huw Lewis AM) and the new Deputy Minister for Skills and Technology is an ex-Alun School pupil (Ken Skates AM)

If you don't believe me, here are the links to the news stories

Huw Lewis is named Wales education minister
Ken Skates Biography on Welsh Government website

I guess it is a career option we can all fall back on if things don't work out for us.

See you all in government

Amphoteric Behaviour and Aluminium

OK, Aluminium ions are amphoteric. Which basically tells you that they will react with acids and bases. The question is though if that is true, how can this be proved using just one chemical (sodium hydroxide). Right lets think this through

Think of aluminium Nitrate. The aluminium ion is the amphoteric bit (not the nitrate).


So, if you start with aluminium nitrate it will turn into aluminium hydroxide (white ppt)

like this...

Al3+  +  3OH-  --> Al(OH)3(s)

Now at this point the aluminium hydroxide could do the obvious thing of behaving like a base and reacting with some acid to make salt and water

e.g.

Al(OH)3  +  HCl  --> AlCl3  +  3H2O

or (and this is the super important/exciting amphoteric bit)

it could react with NaOH and become Al(OH)6 3-

Al(OH)3  +  3OH-  --> Al(OH)6 3-

So adding more OH- proves it is amphoteric because it proves it can do both things.

Any old hydroxide salt can react with an acid but only magic amphoteric ones can react with bases as well

NOTE - Amphoteric compounds aren't magic

Aspirin giving you a headache?

What do you need to know about aspirin?

Almost nothing. Isn't that what you wanted to here.

Aspirin production was in the old spec but has almost completely gone from the new spec. So you will find questions in the old spec CH4 questions about it.

The only thing you need to know is that making aspirin is one of the uses of acid anhydrides.

So remember that fact, laugh in the face of the aspirin based questions and move on.You will feel much better for it

Special Agent (or why is Manganate sometimes used acidified and sometimes in alkaline solution)

Potassium Manganate (VII) is either used acidified (when oxidising alcohols) or in alkaline solution (when oxidising methyl benzene)

The reason why you have to acidify the manganate VII for the oxidation of alcohols is because the reaction needs H+ to combine to make water from MnO4-'s oxygens. As you saw in CH5 when doing redox half equations for Manganate (VII).

The reason why you need alkaline conditions when oxidising methyl benzene - I have no idea. 

I even googled it and found some degree level notes on it and they said the mechanism was to complicated to explain at degree level. So if I was you, I would assume it is wizardry and move on.

Sounds a Bit Fishy (or Naming N-Substituted Amides - CH4)

N-substituted amides are named in two parts (a bit like esters). So lets look at an example

N-methyl ethanamide

If you look at the molecule, it is an ethanamide with a methyl hanging off the Nitrogen

The ethanamide is on the left (with the amide functional group in the middle) and the methyl is hanging off the N of the amide link (hence N-methyl)

If you remember that the chain that is attached to the N is the one which is the "N-...." at the start of the name then that will tell you which chain goes where.

What about working it out from the reactants (i.e. amine and acyl chlorides)

The amine brings in the N so the amine chain will the N-... chain

and the acyl chloride brings in the rest.

TO be honest this rarely come up in CH4 so I wouldn't worry too much about it!

Is it just me or does Rumpelstiltskin look like the hazard symbol for an oxidising agent? (CH5)

Rumpelstitskin                             Oxidising Agent Hazard Symbol

Anyway, back to the science, the best oxidising agent has the most positive standard electrode potential

e.g. Iodine will oxidise anything that is a worse oxidising agent than it. Which is all those with a value of less positive than +0.54v.

When deciding whether things will oxidise things you must compare oxidising capabilities. If you turn the value around you are not comparing like with like. You would effectively be comparing oxidising ability with reducing ability, which makes no sense.

So when deciding what different elements can oxidise look at the values as stated, as the values show the strength of the species as an oxidising agent.

If the question is "What can this species oxidise?"the answer is the name of the more reduced species e.g. Cu, Ni and Fe not Cu2+, Ni2+ or Fe 2+ as that is what would be oxidised.

To finish, a top Shrek quote...

Gingerbread Man: Okay, I'll tell you... Do you know... the Muffin Man?
Lord Farquaad: The Muffin Man?
Gingerbread Man: The Muffin Man.
Lord Farquaad: Yes, I know the Muffin Man. W-who lives down on Drury Lane?
Gingerbread Man: Well, she's married to the Muffin Man...
Lord Farquaad: The Muffin Man?
Gingerbread Man: THE MUFFIN MAN!
Lord Farquaad: She's married to the Muffin Man...

Why aren't all crystal lattices 6:6 or 8:8?

Lets start off with a reminder why NaCl is 6:6 and compare thaty to CaCl2

The NaCl the structure is 6:6 because in that lattice the structure the ions take up is controlled by the size of the smaller Na+ ion and how many Cl- ions you can fit around it, (i .e. Na+ is small so you can only get 6 Cl- around the Na+).

The other number 6 (in 6:6) comes from the fact that to maintain the 1:1 ratio that NaCl must have, you need 6 Na+ around each Cl- too. You could get a lot more Na+ around the Cl- but that would spoil the 1:1 ratio.

(Why must NaCl be 1:1?

Sodium has 1 electron in the outer, which it needs to lose to form a stable ion. Chlorine needs to gain one to from a stable ion. So 1 sodium needs to lose 1 electron to 1 chlorine to be stable. Happy Days.)

Now, lets apply the same logic to CaCl2. Whatever structure CaCl2 takes, it must maintain the 1:2 ratio (for the same reason as above).

The 6:6 structure maintains a 1:1 ratio so it would never work for CaCl2.

You don't need to know the structure CaCl2 takes, all you need to know is, it is not 1:1, so can't be 6:6 (i.e. the same as NaCl.)

"Health and Safety" gone mad

Just to cheer you up if you are revising hard.

If you are not revising hard, get to it.

Dinosaurs didn't revise and they are extinct.

Correlation or Causation?