What kind of ions co-precipitate with chloride?

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In summary, the question asks what ions may co-precipitate with a chloride ion. In this case, the only possible ion is silver chloride.
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Homework Statement



Question: What kinds of ions may co-precipitate with a chloride ion? (List at least two).

This is a question for the theory section of my gravimetric analysis lab.
An unknown chloride salt is mixed into a solution. This solution is to be mixed with a certain quantity of silver nitrate to precipitate out silver chloride, but first the solution is mixed with nitric acid to ensure that no unwanted co-precipitates form. Specifically, the nitric acid is mixed into ensure that any carbonate ions that may be present within the solution are converted to carbon dioxide gas and water (if somebody could tell me why carbonate ions would even be in this solution in the first place, that'd be awesome too). Otherwise, carbonate ions may precipitate to form silver carbonate and the analysis will be ruined.

Homework Equations



I know that in this solution, there are H+ ions, Ag+ ions, Cl- ions and NO3-- ions.
What I'm trying to find are two ions that may form a precipitate with Cl-.

The Attempt at a Solution



I've only been able to find 1 possibility so far, being the formation of NH4Cl.
NH4+ + Cl- --> NH4Cl
Thanks ahead of time for any/all help given.
 
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  • #2
I assume the silver precipitates out along with the chloride ion, since the salt is insoluble and that is the precipitate you are trying to make in this case. Ammonium chloride is soluable in water, so it will not form a precipitate.

Is the analysis below the question different from the question? Many ions co-precipitate with chloride, but the only one I see in the expanded question/analysis is silver.
 
  • #3
Yeah, the goal is to use ALL of the chloride ions from the unknown salt to form silver chloride. However, when the chloride ions are dissociated, they also supposedly interact with other ions in the solution, so not all of them are used in creating the silver chloride precipitate, which results in a certain degree of error.

Sorry if the question's confusing. What I'm asking is: in a solution that contains ONLY the previously mentioned ions (H+ ions, Ag+ ions, Cl- ions and NO3-- ions), what ions exist or can be formed (other than silver ions) that can react with the chloride ions? I'm supposed to provide two examples where chloride ions can be used up in reactions with ions other than silver.
 
  • #4
The more similar the ion, the higher the chance it will coprecipitate. First suspects are halides and pseudohalides. Then every ion that creates low solubility silver salts (that means almost everything).
 
  • #5


In addition to NH4Cl, another possible ion that may co-precipitate with chloride is Fe3+. This can occur when iron(III) chloride (FeCl3) is present in the solution, which can form a precipitate with silver chloride. This can happen if the unknown chloride salt contains iron as an impurity or if iron is present in the solution from other sources.

Other potential ions that may co-precipitate with chloride include sulfate (SO4 2-), which can form a precipitate with silver sulfate, and phosphate (PO4 3-), which can form a precipitate with silver phosphate. These ions may be present in the solution as impurities or from other sources.

As for the presence of carbonate ions, they may be present in the solution if the unknown chloride salt is a carbonate salt, such as sodium carbonate (Na2CO3) or potassium carbonate (K2CO3). These can form when a metal carbonate reacts with hydrochloric acid (HCl), producing both chloride ions and carbon dioxide gas. In the context of the lab, the nitric acid is added to ensure that any carbonate ions present are converted to carbon dioxide gas, which will not interfere with the precipitation of silver chloride.
 

Related to What kind of ions co-precipitate with chloride?

1. What is co-precipitation?

Co-precipitation is a process in which two or more substances are precipitated together from a solution. In this case, chloride ions and other ions are precipitated together.

2. Which ions commonly co-precipitate with chloride?

The most common ions that co-precipitate with chloride are silver, lead, and mercury ions. However, other metal ions such as copper, iron, and zinc may also co-precipitate with chloride under certain conditions.

3. How does the presence of other ions affect the co-precipitation of chloride?

The presence of other ions can significantly affect the co-precipitation of chloride. Some ions may enhance the co-precipitation process, while others may inhibit it. The specific effects depend on the concentration and nature of the other ions present.

4. Why is it important to understand which ions co-precipitate with chloride?

Understanding which ions co-precipitate with chloride is crucial in various fields, such as environmental and analytical chemistry. This knowledge can help identify and quantify the presence of certain ions in a sample and determine the potential formation of insoluble compounds. It also aids in predicting the behavior of chloride in different solutions and conditions.

5. How can co-precipitation of chloride be prevented or controlled?

Co-precipitation of chloride can be controlled by adjusting the pH of the solution, using chelating agents to bind with the other ions, and carefully selecting the precipitating reagent. It is also essential to maintain proper experimental conditions, such as temperature and stirring rate, to prevent the co-precipitation of unwanted ions.

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