Chem notes! here goes...let's see how i try making confusng things clearer in my head.

ok i shall start with the most confusing part. QUALITATIVE ANALYSIS.

Firstly, have to get someting clear in your heads. In the case of cations and anion, most of the compounds that are tested hve 2 sides to it, metal and non metal. metals will form Cations. non metals form anions.

cations with a charge of +
All grp 1 ions
1. Sodium
2. potassium
3. lithium
4. hydrogen
5. silver
6. Ammonium (NH4+)
7. copper(I)

Basically, group 1 ions will have a charge of positive 1.Grp 2 ions have charge of 2+. Grp 3 METAL ions have charge of 3+ (i have no idea abt Boron. anyone ha any idea?) Transition metals have a charge of whatever is in the bracket beside them. For example, an ion called jiawei (VII) will have a charge of 7+.

Anions
charge of 1-:
-all halogens (grp VII)
-hydroxide (OH)
-nitrite (NO2)
-Manganate (VII) MnO4
-Nitrate (NO3)

charge of 2-:
-group VI non metals
-Carbonate (CO3)
-sufate (SO4)
-sulfide (SO3)
-chromate (VI) (CrO4)
-Dichromate (VI) Cr2O7

charge of 3-:
-grp IV ions
-nitride (N) (NOTE, NITRITE AND NITRATE WITH A T HAS OXYGEN)
-phosphate (PO4)

ok now is the part with loads of memorising. IDENTIFYING CATIONS!!
so basically, cations are metal ions right, with positive charge. They ae identified by 2 main things: Sodium hydroxide solution (NaOH) and Ammonia NH3 (aq). Firstly let's deal with sodium hydroxide.

When it is added, no ppt:
K+ and Na+ (surprisingly, these 2 are the most reactive atoms! they have no ppt in ammonia either)

white ppt:
soluble in excess NaOH: (note: these are teh only ppts that are soluble in excess NaOH!)
-Zn2+ (unique point is that in excess aq ammonia, it's white ppt can dissolve)
-Al3+
-Pb2+ (when mixed with iodide with nitric acid and heated, bright yellow ppt forms. On boiling, ppt dissapears, but on cooling under tap water, golden crystals appear)

Blue ppt (insoluble)-Cu2+ (copper (II) ions)
Dirty green ppt (insoluble)- Fe2+ (note: in contact with air, the top layer is oxidised to form Fe3+ look below, thus have reddish brown colour)
Reddish brown ppt (insoluble)-Fe3+

ok so in summary, for cations (metal ions) in sodium hydroxide, all ppts are insoluble except for Zn, Al and Pb. Those cations with a charge of positive 1 usually have no ppt. ppts formed are formed by the cation itself+ hydroxide (OH-), thus by doing the balancing chemcal reaciton thing, cations X of charge y will form the ppt: X(OH)y (s). so it's like, calcium hydroxide, zinc hydroxide etc.

ok now we come to the aq ammonia.

no ppt:
-the same 3: Na, K, NH4
-Ca2+ (prreviously it had white insoluble ppt) (oh and, it does have a slight white ppt in NH3)

white ppt: (these 3 were previously insoluble white ppl in NaOH)
soluble: zn
insoluble: Al and pb

Blue ppt (soluble in excess NH3 to form dark blue solution)- Cu2+
Dirty green ppt (insoluble in excess NH3)- Fe2+ (same as NaOH)
Reddish brown ppt (insoluble in excess NH3 )- Fe3+ (same as NaOH)

summary, only 2 of them are soluble in excess--Cu2+ and Zn2+. ppts are still called something hydroxide.

thus, when testing for cations, these are some of the unique points to differentiate between cations.

NH4- almost the same as K and Na, just that in NaOH, when warmed, ammonia gas is evolved
Zn-white ppt insoluble in excess Ammonia (special!)
Pb- when added to a mixture of iodide and nitric acid, bright yellow ppt forms. ppt dissolved upon heating, and reappear as yellow crystals upon cooling)

ok that's all for cations! now it's time for anions!

ANIONS. hmm...i'm now trying to figure out what it's all about...ooohhh...only have about 5-6...

First up, CARBONATE:) CO3 2-
this one is quite easy. Just add acid and test for carbon dioxide (limewater test).

Second, we have...CHLORIDE!
not that complicated either. basically, add silver nitrate (aq) to the chloride solution. WHITE ppt (silver chloride) is formed. the ppt is insoluble in acid, but dissolves in aqueous ammonia to form colourless solution.

Third, Sulphate! (So4 2-)
add barium nitrate or chloride solution to sulfate solution. add acid. white ppt is formed (barium sulphate). ppt is insoluble in excess acid.

4:: IODINE!
hmm ok this one, it's brought up just now in the cations part if you noticed. there are 2 ways. the most common one is to add aq lead nitrate to it, there will be bright yellow ppt which is lead iodide. it will dissolve when heated, but reappear as golden crystals when cooled! (nice:)) second method is to use silver nitrate. Add silver nitrate to it, and there will be pale yellow ppt. (silver iodide) it is insoluble in acid and ammonia.

5. last one! nitrate!
ahh this is easy! just don't get comfused with ammonium ion, whihc is a cation. this is nitrate, anion!! NO3 -. The procedures are same for testing for ammonium ion (NH4) jus that after step 1, adding NaOH, add DEVARDA's ALLOY (Al andZinc), or Aluminium. warm the mixture, and ammonia will be released. for ammonium ion, htere is NO metal to be added!

ok so in conclusion, i have one final conclusion to end this post. memorise. it's the only way, unfortunately...but wait! don't be sad! smile!:D yep that's right. If things are already the way it is, ther'es no point being sad over it right? smile! smiling is good for you! it makes you feel happy, energetic, youthful! and seriously, whenever you really feel very sad or angry or pissed, just put on a fake smile, and things will kind of clear, like, suddenly you won't be so angry anymore!!:D ok so yea, spread the smile, make the earth a happier place!:)

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