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# Mendelejev

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85

1. ## Chemistry problem - formal charges

To obtain the formal charge of an atom in a compound : just count how many bonds there are + the number of free electrons. And compare that number with the number of valence electrons. In his example S has six bonds (a double bond with oxygen counts for two.) and no free electrons. So a total of six. S, group VIa, so six valence electrons. 6 - 6 makes a formal charge of 0. Oxygen had one bond with S, six free electrons, total is 7, but group VIa, so 6 - 7 is -1 => formal charge of oxygen. Other oxygen had two bonds with S, four free electrons, total is 6, so formal charge of 0 The sum of all the formal charges is the charge of the compound. Here 0 + 0 + 0 - 1 - 1 = a total of -2. Correct, becouse SO4 is SO4 2-
2. ## Synthesis of NaI

Think I'll just go to the chemistry shop (Don't have friends with a Birkeland-Eyde reactor at home )
3. ## A colored gas, containing chromium

Correct. I have some old books of "chemistry", almost "kitchen chemistry", in fact a mix of alchemy an chemistry and cooking. But extremely interesting !! The first chapter is "Het vervalschen van goud' ! Means : 'adulterating (?) gold' with some common metals. I search in old bookstores, but it's hard to find old books on chemistry. Maybe if I go to Germany, I could find something interesting. Becouse, yes it's true, during WWII, the germans were very good in chemistry (think of Haber for example), and they have written some great books. Also the book of Oliver Sacks 'Uncle tungsten' is a nice book. Not really descriptions of the experiments, but it could give you some new ideas. Schoolbooks for the basic experiments. History books, for old experiments, like Hennig Brand's extraction of P
4. ## A colored gas, containing chromium

Mmm, very nice experiment. I'm certainly going to try it ! I'll let you know if it worked well or not. But I was wondering. Aren't there nice experiments with chromyl chloride for example ?? Would be nice
5. ## Calcium Concentration

Yeah, EthyleneDiamineTetraAcetic acid Thanx, I hate it when I forget something like that

7. ## Calcium Concentration

And are you really going to use bodily fluids ?? At school ??
8. ## Calcium Concentration

EDTA is a ligand. Some 'chelated' complexed ions have EDTA as ligands. I'm searching for the full name of EDTA, but can't find it anymore
9. ## organic experiments

Well, I have a lot of formic acid. Could I do some nice experiments with it or not ? I also have ethanol, methanol, acetic acid (vineagar). But that's almost everything. (I have more inorganic products.)
10. ## Synthesis of NaI

Mmm, a plasma arc. Don't think I've got that in my lab.
11. ## sharpie solvent

Indeed, and when it's on the second C of the chain, instead of the first, we call it iso-... For example CH3-CH2OH-CH2-CH2-CH3 is iso-pentanol (or 2-pentanol) (or 2-hydroxo-pentane, but I don't think it's what the IUPAC wants)
12. ## How are radical valencies solved?

Yes, indeed. So one half of all the elements we can collect are radicals. Chlorine for example, has a valency of zeven, so 3 pairs of two electrons and 1 apart, the radical.
13. ## Synthesis of NaI

Mmm, thanx a lot for the information. But don't forget H202. Are there simple and cheap methods for his synthesis ??
14. ## Who was the greatest scientist or inventor that ever lived ?

YES, INDEED !!! People always tend to forget her, but without her scientific research, watson and crick would never have been able to discover the strucure of DNA.
15. ## Synthesis of NaI

I would like to make H202 with very cheap chemicals. Also NaI ! Does someone knows a good method ??
16. ## Element Zero

Yes, indeed, it could NEVER form a stable element. So, we could remove the electron. Problem solved, but you obtain just a neutron, and that is indeed just an elemental particle, NOT an element.
17. ## Suggestions for primary school science experiments?

Making a volcano with vinegar and baking soda is GREAT. I love that experiment, not dangerous, spectacular, ... ! You could even make a volcano with plaster. http://www.spartechsoftware.com/reeko/Experiments/volcano.htm You can even buy a set http://www.miniscience.com/projects/volcano2/ You could also make some volcano's with ammonium dichromate but it's more dangerous and carcinogen. http://www.west.net/~science/volcano.htm Or you could do the famous menthos-eruption http://www.stevespanglerscience.com/experiment/00000109 Or use some hydrogen peroxide and add some NaI ! Works very very well.
18. ## Solution of Plastic

I've tried to make a solution of the glow-in-the-dark-plastic with acetone, but I had to scratch some of the plastic of the stars, and I obtained a sort of gummy ball. So it certainly didn't disolve in acetone. I think I'm going to try it with petrol like YT2095 said.
19. ## Chlorine

Yes, indeed, but worse
20. ## Chemical calculator poll

lol, I don't think it's worth a few thousand dollars
21. ## solubility

I don't think so. I've always learned that something (NaCl for example) will desolve a lot better in hot water, becouse the water molecules are moving more heavily and faster. But ... (think, think), in fact, maybe you are correct. Becouse my theory could explain the fact that the salt will be disolved a lot faster. But it doesn't explain why there can disolve more of the salt !!?
22. ## Bismuth Crystals

mmm, yeah. I think I've heated it a little to much. So, if I understand. You put some of your bismuth in a flask, heat it with a bunsen flame, BUT not to much, when it begin to melt, stop heating. And wait until the liqiud Bi forms crystals. Correct ?
23. ## thermite won't ignite

Yes, indeed. I was confusing the two methods I've tried so far. 1. Sugar + KClO3 and some drops of sulfuric acid 2. Glycerin and potassium permanganate.
24. ## thermite won't ignite

I use sugar, some glycerin and H2SO4 instead of Mg. That works great !!
25. ## Bodily Extracts

Mmm, sounds interesting. I'll try it some day.
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