Chapter 17: Problem 63
In a group 1 analysis, a student obtained a precipitate containing both \(\mathrm{AgCl}\) and \(\mathrm{PbCl}_{2}\). Suggest one reagent that would enable her to separate \(\operatorname{AgCl}(s)\) from \(\mathrm{PbCl}_{2}(s)\)
Short Answer
Expert verified
Hot water can be used to separate \(\mathrm{AgCl}\) from \(\mathrm{PbCl}_{2}\).
Step by step solution
01
Understanding the Components
The precipitate contains both silver chloride (\(\mathrm{AgCl}\)) and lead(II) chloride (\(\mathrm{PbCl}_{2}\)). These are both insoluble chloride salts that can be separated based on their solubility differences in certain solvents.
02
Analyzing Solubility Properties
Silver chloride (\(\mathrm{AgCl}\)) is highly insoluble in water, while lead(II) chloride (\(\mathrm{PbCl}_{2}\)) is somewhat more soluble, especially in hot water. This means thermal manipulation can be explored for separation.
03
Identifying a Suitable Reagent
Since \(\mathrm{PbCl}_{2}\) is more soluble in hot water, heating the mixture and filtering allows \(\mathrm{PbCl}_{2}\) to dissolve in the hot water, leaving \(\operatorname{AgCl}(s)\) as a precipitate. Thus, hot water can be used as a reagent to separate the two.
04
Procedure for Separation
The mixture containing \(\mathrm{AgCl}\) and \(\mathrm{PbCl}_2\) is shaken with hot water. \(\mathrm{PbCl}_2\) dissolves and can be filtered off as the solution, leaving solid \(\operatorname{AgCl}(s)\) behind. Upon cooling, lead(II) chloride can eventually recrystallize.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Solubility
Solubility refers to the ability of a substance to dissolve in a solvent, forming a solution. It is an important property in chemical separation techniques. Different substances have different solubilities based on factors such as temperature, pressure, and the nature of the solvent.
- For instance, \( \text{AgCl} \) is significantly less soluble in water compared to \( \text{PbCl}_2 \).
- This difference in solubility is crucial for separating these compounds.
Group 1 Analysis
Group 1 analysis is an important aspect of qualitative inorganic analysis. It involves identifying specific ions present in a mixture and is often applied to ions that form insoluble chlorides, like silver and lead ions.
- In this type of analysis, common reagents are used to selectively precipitate ions based on different properties.
- For \( \text{AgCl} \) and \( \text{PbCl}_2 \), both are considered in Group 1 because they form precipitates with chloride ions that are typically insoluble.
Precipitation
Precipitation is the process where a soluble substance forms an insoluble solid upon reaction, known as a precipitate. It's a key technique used in chemistry to separate different substances from a solution or mixture.
- For example, when chloride ions are added to solutions of silver or lead, \( \text{AgCl} \) and \( \text{PbCl}_2 \) precipitate out.
- In the context of this analysis, precipitation is essential for isolating these compounds from the rest of the solution.
Filtration
Filtration is a straightforward and essential technique used to separate solids from liquids, crucial in isolating precipitates. It involves passing a mixture through a filter that allows the liquid to pass while retaining the solid on the filter.
- When \( \text{PbCl}_2 \) dissolves in hot water, filtration can be employed to separate \( \text{AgCl} \) from the solution containing dissolved lead chloride.
- The solid \( \text{AgCl} \) remains as a residue, while the liquid filtrate contains dissolved substances.