Qualitative analysis lab, zinc problem

In summary, the conversation is about a qualitative analysis lab where the unknown solution can contain various ions and the tools and chemicals available for testing. The person has been able to figure out all the cations except for zinc and is trying to find a way to test for it without being masked by other cations.
  • #1
will1530
1
0

Homework Statement



This is for a qualitative analysis lab. The unknown solution can contain any combination of the following ions: Na, Mg, Ni, Cr, Zn, Ag, Pb, NO3, Cl, I, SO4

Tools available: Bunsen burner for flame test, centrifuge, hot plate, and all the test tubes and DI water you could possibly want.

Chemicals available to add: The Na+ or NO3- solutions for all the above ions, HNO3, HCl, NH3, NaOH, saturated AgSO4 solution, and 18M H2SO4.


The Attempt at a Solution



I have been able to figure out any combination of the above except for zinc. In every other cation qual lab we've had a known number of cations and the strategy was to simply figure out all the cations you can and if you have an extra slot throw zinc into it and you'll be correct if you did everything else right. Now we have to figure out a way to test for zinc that won't be masked by any other cations. The only thing I can think of is to try to flame test for it, but that doesn't seem very practical in a bright lab with other ions potentially in solution.
 
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  • #2
will1530 said:

Homework Statement



This is for a qualitative analysis lab. The unknown solution can contain any combination of the following ions: Na, Mg, Ni, Cr, Zn, Ag, Pb, NO3, Cl, I, SO4

Tools available: Bunsen burner for flame test, centrifuge, hot plate, and all the test tubes and DI water you could possibly want.

Chemicals available to add: The Na+ or NO3- solutions for all the above ions, HNO3, HCl, NH3, NaOH, saturated AgSO4 solution, and 18M H2SO4.


The Attempt at a Solution



I have been able to figure out any combination of the above except for zinc. In every other cation qual lab we've had a known number of cations and the strategy was to simply figure out all the cations you can and if you have an extra slot throw zinc into it and you'll be correct if you did everything else right. Now we have to figure out a way to test for zinc that won't be masked by any other cations. The only thing I can think of is to try to flame test for it, but that doesn't seem very practical in a bright lab with other ions potentially in solution.

What have you done to remove the other cations?
 

1. What is qualitative analysis lab and how is it used?

Qualitative analysis lab is a laboratory technique used to identify and determine the chemical components of a substance. It involves observing the physical and chemical properties of a sample and comparing them to known standards to determine the presence of certain elements or compounds.

2. What is the "zinc problem" in qualitative analysis?

The "zinc problem" refers to the difficulty in detecting and identifying zinc ions in a sample during qualitative analysis. This is because zinc ions form colorless or white precipitates with most reagents, making it challenging to distinguish from other colorless ions.

3. How is zinc typically detected in qualitative analysis?

Zinc is typically detected in qualitative analysis by using a combination of reagents and observation of physical properties. Some common methods include using potassium ferrocyanide to form a blue precipitate, or adding sodium hydroxide to form a white precipitate that dissolves in excess to form a colorless solution.

4. What are the potential sources of error in qualitative analysis for zinc?

Potential sources of error in qualitative analysis for zinc include contamination of the sample, incorrect measurement or mixing of reagents, or interference from other ions present in the sample. It is important to carefully follow the proper procedures and controls to minimize these errors.

5. How can the results of qualitative analysis for zinc be verified?

The results of qualitative analysis for zinc can be verified by performing confirmatory tests, such as adding a known zinc-containing solution to the sample and observing for the expected reaction. Additionally, repeating the analysis multiple times and comparing the results can also help to verify the accuracy of the findings.

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