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The old conquering chemistry textbook I think. Why do you care...ex-HSC person? Are you considering a future in water monitoring and management? ;)

Anything under 500 ppm phosphate is considered healthy.

Crap, that's unusually SMALL for phosphate concentration of POLLUTED WATER (?)

Actually, how did you get that??? 0.025 * 1000 / 0.1 = 250 ppm!!!??

CRAP, sorry McLake, I meant to say 0.1 L or 100 ml. But according to your working, I think you are correct.

I did this experiment to find the concentration of various ions in a water solution as part of an independent investigation. NOW... It's kinda tricky with PO4 ions because of the 3- valency. This is because (in the experiment I did), I formed a compound of Barium Phosphate, meaning my end...

I think I follow now. Thanks!

Hmm, I did not get that. Don't you add 7! twice for both 0 and 1 a's scenarios? I worked it out a totally different way and did not quite get what you got.

This was in the 4 U test at my school, but it's more harder 3 U work. How many ways can you arrange 6 letters taken from the word AUSTRALIA? I got a fair idea of what the answer is, but I'd like to see what the rest of you think.

I've overseen most of the course and have done the first 2 core topics. It isn't that bad. But I guess it was beneficial for you in that you averted making the wrong decision in life. Perhaps you should be grateful of the chem course?

I'm doing the HSC course now. I know some things can be burdensome, but if one develops an interest, you can't go wrong. You probably shouldn't have chosen chemistry if you weren't prepared to "memorise" such facts. If you had a genuine interest in the subject, you'd remember it automatically...

Well thanks, but to be on the safe side, I shall consult some of my sources to verify it. And you didn't say you were the chem guru, you said you were the HSC guru, which ENCOMPASSES chemstry...HAW HAW HAW HAW HAW!!!

Tsk Tsk, you call yourself the "HSC Guru"...

But what about the Mg ions? Why doesn't the Na2CO3 form precipitates with other dissolved cations?

The TDS experiment is kinda dodgy. I don't want to do it the electricity way because that doesn't show me anything except a value which I can look at. I don't want to evaporate it because the yield of solids will be quite small. The hardness idea you got there I have not heard of. And...

Must you make your statement so general? It may be gay for you, but frankly, I find it interesting. Don't forget, chemistry makes the world go around...OR DOES IT?! Well...yes, it does, amongst other things..

Ok, it seems like my far-out and different idea is taking me no where. I basically have to look for factors influencing water quality and make up an experimental test to determine such factors. What's more, I have to perform the experiment. Now, I've done pH, which was easy. I think my...

Well it would actually be harder to find one of them specifically, as most tests, such as the addition of sodium sulphide will actually result in the formation of more than one precipitate.

Actually, what I really meant to say was the % composition of the overall heavy metal content. And yeah, there's a big problem- I can't just presume they're all valence 2. Hmm, can any suggest a way to quantitatively determine the amount of heavy metal in the water sample? Mclake...perhaps?

I have a water sample from my local creek. Now basically, I have to somehow quantitatively find the % composition of heavy metals in the sample. I've filtered out the large impurities. I've added the nitric acid and sodium sulfide. The precipitate of various heavy metal sulfides have formed...