Qualitative analysis of Barium, Strontium, Calcium

In summary, during qualitative analysis of Barium, Strontium, and Calcium, we use NH4CO3, NH4OH, and NH4Cl to completely describe the reactions that occur in the test tube. This ensures that we are able to accurately determine the presence of these elements in the sample. The third NH4Cl may be necessary to fully precipitate the desired compound and ensure the success of the analysis.
  • #1
chound
164
0
During qualitative analysis of Barium, Strontium, Calcium, why do we use NH4CO3, NH4OH, NH4Cl. Even if we were to apply common ion effect, two NH4+ ions are enough right? What is the need for third one?
 
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  • #2
I assume that you are referring to the ammonium chloride?

It might be there to completely describe what you might expect to find in your test tube after adding NH4OH or NH4CO3 [(NH4)2CO3? or (NH4)HCO3?] to your unknown which is probably a soluble chloride salt.

eg.

Sr(Cl)2 + 2NH4OH -----> Sr(OH)2(s) + 2 NH4Cl

Ca(Cl)2 + (NH4)2CO3 -----> CaCO3(s) + 2 NH4Cl
 
  • #3


During qualitative analysis of Barium, Strontium, and Calcium, we use NH4CO3, NH4OH, and NH4Cl because they act as precipitating agents for these ions. This means that they help to form insoluble salts with these ions, allowing us to identify their presence in a solution.

The use of NH4CO3, NH4OH, and NH4Cl is necessary because each of these ions has different solubility properties. For example, Barium forms an insoluble carbonate salt with NH4CO3, while Strontium forms an insoluble hydroxide salt with NH4OH. Calcium, on the other hand, forms an insoluble chloride salt with NH4Cl.

The common ion effect is not the only consideration when choosing these precipitating agents. The solubility of the resulting salt also plays a crucial role. In some cases, the common ion effect may not be strong enough to precipitate all of the ions present. Therefore, the use of a third precipitating agent is necessary to ensure that all of the ions are effectively removed from the solution.

In conclusion, the use of NH4CO3, NH4OH, and NH4Cl in qualitative analysis of Barium, Strontium, and Calcium is essential for their ability to form insoluble salts with these ions and to ensure complete precipitation. The common ion effect is just one factor to consider, and the solubility properties of the resulting salts also play a crucial role in the choice of these precipitating agents.
 

Related to Qualitative analysis of Barium, Strontium, Calcium

1. What is qualitative analysis?

Qualitative analysis is a method used in chemistry to identify the presence or absence of certain elements or compounds in a sample. It involves observing and describing the physical and chemical properties of the sample, rather than measuring exact quantities.

2. Why is qualitative analysis important for studying barium, strontium, and calcium?

Barium, strontium, and calcium are all important elements with various applications in industries such as medicine, agriculture, and construction. Qualitative analysis allows us to determine the presence of these elements in a sample, which can provide valuable information about the sample's composition and potential uses.

3. What techniques are commonly used in qualitative analysis of barium, strontium, and calcium?

Some common techniques used in qualitative analysis of these elements include flame tests, precipitation reactions, and complexometric titrations. These methods involve introducing a reagent to the sample and observing any changes in color, texture, or other properties that indicate the presence of the element.

4. What are some potential sources of error in qualitative analysis of barium, strontium, and calcium?

Potential sources of error in qualitative analysis include contamination of the sample, incorrect measurement of reagents, and improper calibration of equipment. It is important to carefully follow procedures and repeat experiments to ensure accurate results.

5. How is qualitative analysis of barium, strontium, and calcium different from quantitative analysis?

Qualitative analysis focuses on identifying the presence or absence of specific elements or compounds in a sample, while quantitative analysis involves measuring the exact amounts of these substances. Quantitative analysis provides more precise and quantitative data, while qualitative analysis is more useful for identifying unknown substances or monitoring changes in a sample.

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