identify the samples (1 Viewer)

[AnAn]

1)i 've got solid sample of zinc nitrate, barium chloride, calcium carbonate and sodium carbonate. given that bottles of distilled water, hydrochloric acid an lime water. how do i know which sample is which??

2) can anyone describe what is meant by an absorption spectrum for me pls??

3)why we need to monitor levels of certain ions in our water ways??

thx for help~~

 

[Xayma]

1) Well if you can get the weight of each it is so much easier.

Calcium Carbonate (CaCO₃) reacts with HCl as follows:

CaCO_{3 (s)}+2HCl_(aq)--> CaCl_{2 (aq)}+H₂O_(l)+CO_{2 (g)} bubble the gas through limewater to prove it is CO₂.

Na₂CO_{3 (s)}+2HCl_(aq)--> 2NaCl_(aq)+H₂O_(l)+CO_{2 (g)}, however CaCO₃ is insoluble in water so you can distinguish between those two that way.

Barium Chloride wont react with the HCl as far as I know.

Zinc Nitrate will however. (someone correct me if Im wrong).

2) Do you do physics, if you do it makes it alot easier but anyway.

The electrons require a certain amount of energy (and hence a certain frequency of light) to jump from one energy to the next, it will only absorb those frequencies, as the energy levels are unique per atom, it can identify the atom by basing it on what frequencies of light it absorbs.

3) Some are toxic particularly the heavy metals in very low concentrations.

 

[TheKing]

uh... i think your looking at identify the annions( maybe cations i get confused)
but basically look up the solubility rules again, they hlp ALOT and you will find out which ones precipatate with what and therefore identify them.

 

[gershy]

I think that if you add the zinc nitrate solution to the lime water ( calcium hydroxide solution) you will get a precipitate of zinc hydroxide. This won't happen with the barium chloride as barium hydroxide is soluble. So if you combine Xayma's tests with mine you get them all identified.

 

[aloquacious]

hey anan, do u go to prior? cuz a LOT of ur q's sound familiar