What Are the Solubility Rules for Predicting Precipitate Formation?

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Discussion Overview

The discussion revolves around the solubility rules for predicting precipitate formation when mixing solutions in a chemistry context. Participants explore the implications of solubility rules, the concept of infinite solubility, and the calculations involved in determining whether a precipitate will form.

Discussion Character

  • Homework-related
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions whether solubility rules imply that certain substances have infinite solubility when mixing solutions.
  • Another participant asserts that nothing has infinite solubility and references solubility data from tables, indicating that solubility is measured in specific units.
  • A participant distinguishes between infinite solubility and miscibility, noting that the concept applies more to liquids than solids.
  • There is a suggestion that soluble substances are ignored in calculations because they are significantly more soluble than others, but this is not universally accepted.
  • One participant provides examples of soluble salts, such as Na+ salts and nitrates, and discusses the process of identifying potential precipitates when mixing solutions.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the implications of solubility rules regarding infinite solubility, and there are competing views on how to approach the calculations for precipitate formation.

Contextual Notes

Participants express uncertainty about the definitions and implications of solubility rules, and there are unresolved questions about the calculations of Qsp and Ksp for different products.

ThatDude
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Homework Statement


Ok, so basically, our teacher gave us some solubility rules... then we did a problem where we mixed two solutions and checked to see if a precipitate would form.

So he calculated Qsp for one of the products and compared it to Ksp for that product, he did not calculate Qsp and Ksp and forth 'other'... this 'other' product obeyed the solubility rules.

So from what I understand, when you mix two solutions to see if a precipitate forms, you ignore the soluble products because they have infinite solubility?

I mean, do the solubility rules tell us that those substances have infinite solubility?
 
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ThatDude said:

Homework Statement


Ok, so basically, our teacher gave us some solubility rules... then we did a problem where we mixed two solutions and checked to see if a precipitate would form.

So he calculated Qsp for one of the products and compared it to Ksp for that product, he did not calculate Qsp and Ksp and forth 'other'... this 'other' product obeyed the solubility rules.

So from what I understand, when you mix two solutions to see if a precipitate forms, you ignore the soluble products because they have infinite solubility?

I mean, do the solubility rules tell us that those substances have infinite solubility?
Nothing has infinite solubility.

If you look in tables (like in the CRC Handbook) you will see solubility data given, units will be something like grams per kg water, or grams per liter.
 
In a way infinite solubility is miscibility. But its not about solids dissolved in liquids, but about liquids dissolved in liquids.
 
Ok. So infinite solubility doesn't exist, but in the original case mentioned, we ignore the soluble substance because its just way more soluble, correct?
 
ThatDude said:
Ok. So infinite solubility doesn't exist, but in the original case mentioned, we ignore the soluble substance because its just way more soluble, correct?

Na+ salts are very soluble, nitrates are soluble, ... Some things are very soluble, many things are insoluble. Generally when you are trying to mix two liquids together, you will have an anion paired with something like sodium cation and a cation paired with something like nitrate. Mixing the two will give you e.g. "sodium nitrate" as one candidate for froming a precipitate (it won't because it si really soluble) and another candidate -- e.g. AgCl (like if you mixed silver nitrate with sodium chloride). As you do more of these things you will learn to recognize the likely culprit from the innocent bystander -- like any good detective!
 

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