Some qualitative analysis help

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In summary: Finally, you can confirm the presence of specific cations and anions by running additional tests on a third sample.In summary, the conversation discusses an experiment to identify an unknown substance that may contain various anions. The speaker used different methods to test for the presence of sulfate, but it is unclear if it was actually present or if another substance was formed. They suggest splitting the unknown into multiple samples to avoid detection of reagents from previous tests.
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bc89
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hi, so we had a general anion unknown to do that may contain 5 of the following: carbonate, sulfite, chloride, bromide, iodide, oxalate, chromate, sulfide, sulfate, phosphate, nitrate, nitrite, chlorate, acetate, and thiocyanate. I am positive that my unkown had phosphate, iodide, and thiocyanate, and when i tested for sulfate i removed iodide and thiocyanate, removed excess silver ion from past steps by precipitating it out with NaCl, made the soln acidic, added CaCl2, then i added BaCl2 and got NO PRECIPITATE. But then i used another method which was add AgNO3 to my unknown, centrifuge, add HNO3 to the soln, then add BaCl2, and i got a white fluffy precipitate that was insoluble in 6M HNO3, 12M HCl and i heated it in a water bath and it did not dissolve. so my question is did i have sulfate? or could i have reduced/oxidized thiocyanate to sulfate in that step? but i don't think i used any oxidizing/reducing agents in that step, or could it have been some other ppt..??
 
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In your second analysis you added Ag and then added a source of chloride. You ppd AgCl. Try dissolving that fluffy stuff in ammonium hydroxide. My guess is that it will be soluble. Not sulfate unless you have some undissolved stuff after you add the ammonium hydroxide.
 
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You'll notice that you identify which cations are present by combining them with various anions and observing the results, likewise you identify the anions present by reacting them with various cations.
If you try to run both sets of tests on one test tube of solution, the second set of tests will invariably detect all the reagents you used in the first set.

The way around this is to split your unknown into two samples, then test one sample for cations only and the other sample for anions only.
 

1. What is qualitative analysis?

Qualitative analysis is a research method that involves collecting, organizing, and interpreting non-numerical data to understand social and behavioral phenomena. This approach is used to gain a deeper understanding of a topic, rather than simply measuring and quantifying it.

2. Why is qualitative analysis important?

Qualitative analysis allows researchers to explore complex and nuanced topics that cannot be fully understood using quantitative methods. It also provides a more holistic and in-depth perspective, as it considers the context and individual experiences of participants.

3. What are some common techniques used in qualitative analysis?

Some common techniques used in qualitative analysis include interviews, focus groups, observations, and document analysis. These methods allow researchers to gather rich and detailed data from participants, which can then be analyzed and interpreted for patterns and themes.

4. How is reliability and validity addressed in qualitative analysis?

Reliability and validity are addressed in qualitative analysis through methods such as member checking, triangulation, and peer debriefing. These techniques help to ensure the credibility and trustworthiness of the data and findings.

5. What are some limitations of qualitative analysis?

One limitation of qualitative analysis is that it can be time-consuming and resource-intensive. It also relies heavily on the skills and interpretation of the researcher, which can introduce bias. Additionally, findings from qualitative analysis may not be generalizable to larger populations.

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