Identification of group 2 metal salts

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Discussion Overview

The discussion revolves around the identification of unknown group 2 metal salts, referred to as X and Y, through various chemical tests. Participants explore the implications of their experimental observations, including the reactions with dilute NaOH, AgNO3, and BaCl2, and consider the solubility and precipitation behaviors of these salts.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant notes that Y formed a precipitate with NaOH while X turned colorless, suggesting different solubility behaviors, possibly indicating that Y contains an ion that is insoluble with OH-.
  • Another participant questions whether X and Y are necessarily salts or if they could also be oxides or hydroxides, and raises concerns about the concentration of NaOH used in the experiments.
  • It is suggested that the addition of AgNO3 could indicate the presence of halide ions in X and Y, while BaCl2 could reveal the presence of sulfate.
  • One participant proposes that X might be BaSO4, which is generally insoluble in water but questions the reaction that would occur with NaOH.
  • Another participant corrects themselves, indicating uncertainty about the identity of X and emphasizes the need for more information.

Areas of Agreement / Disagreement

Participants express differing views on the identities of salts X and Y, with no consensus reached on their exact nature or the implications of the experimental results. Several hypotheses are presented, but the discussion remains unresolved.

Contextual Notes

Participants highlight limitations in the data provided, such as the need for more specific information about the concentration of NaOH and the nature of the salts being tested. There is also uncertainty regarding the classification of group 2 elements and their compounds.

david18
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Hi, I carried out a couple of experiments with unknown group 2 salts; X and Y

I added dilute NaOH to each of the salts which were now mixed with 1cm^3 of water; Y formed a precipitate (initially the solution was colourless as the solute had dissolved) whilst X turned colourless (X's solution was initially insoluble and was therefore a ppt before)
What conclusions could I draw from these observations? I think it might have something to do with Y having an ion that is insoluble when added to OH (ie Be and Mg) and vice versa... but I am not too sure...

Another test was adding AgNO3 + nitric acid, and in another I added BaCl2 - what could these show me?
 
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david18 said:
Hi, I carried out a couple of experiments with unknown group 2 salts; X and Y

I added dilute NaOH to each of the salts which were now mixed with 1cm^3 of water; Y formed a precipitate (initially the solution was colourless as the solute had dissolved) whilst X turned colourless (X's solution was initially insoluble and was therefore a ppt before)
What conclusions could I draw from these observations? I think it might have something to do with Y having an ion that is insoluble when added to OH (ie Be and Mg) and vice versa... but I am not too sure...

Another test was adding AgNO3 + nitric acid, and in another I added BaCl2 - what could these show me?
Very difficult question with only these data.

1. X and Y are necessarily salts or can also be oxides/idroxydes?
2. group 2 include also 2b, that is Zn, Cd, Hg?
3. How dilute is NaOH? Can you specify better the concentration or the pH of the solution?

About substance X: an insoluble group 2 salt that dissolves with diluted NaOH, have I understood correctly?

Berillium idroxyde, carbonate, phosphate are insoluble but dissolves in high alcaline solutions ( not very diluted, then). The same with Zinc, for example.

About Y, there are many elements and many salts for every of those elements which dissolve in water and precipitates with OH-:

Mg (alogenides, nitrate, sulfate), Ca (alogenides, nitrate), Cd (alogenides, nitrate, sulfate), Hg (Hg(II) alogenides, nitrate).

Be and Zn precipitates with diluted sol. of OH- and re-dissolves in high con. of OH-.
 
AgNO3 will help you to find out if there are halide ions (chloride, iodide, bromide,..) in the salts X and Y.

BaCl2 will tell you if sulphate is present.

These two tests determine the anions.

the test with NaOH will help to distinguish the cation.
and i think Y is MgCl2 or MgSO4. you will know that when you test the anion. A white ppt. is formed when you add the Mg salt to NaOH.

This appears to be a school lab experiment. simple and easily available reagents are involved.
 
Last edited:
Kushal said:
i think X is BaSO4. BaSO4 is insoluble in water, but when you add NaOH, it dissolves.
I don't think so. Which should be the reaction?
 
o yeah, of course, X is NOT BaSO4, i will correct that right here. i think more information is required. sorry
 

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