Solving Solubility Doubt: Sodium Benzoate vs. Toluene

In summary, the conversation discusses the solubility of sodium benzoate in water and toluene. The book answer states that it is true, but the speaker is unsure of how to compare the solubility. They mention that sodium benzoate is ionic and water is polar, but it also has an aromatic nucleus similar to toluene. The speaker questions if they are thinking incorrectly and asks for clarification on how to compare the solubility. The other person responds that if a substance is ionic, it is generally soluble in polar solvents, but there is a cutoff for solubility with larger, more complex molecules. Computational chemistry is needed to determine this cutoff.
  • #1
jaumzaum
434
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I was solving an exercise where I had to judge (true or false) 5 statements. One of them said:

"Sodium benzoate is more soluble in water than in toluene"

The book answer is true, but I don't know how to compare it.

I mean, sodium benzoate is ionic, and water is very polar, so the solubility of the salt in water should be great. Nevertheless sodium benzoate has a aromatic nucleus, that is the same of toluene, so they should share pretty much the same molecular interactions and one should reasonably dissolve another too. Am I thinking wrong? If not, how should I compare both of the solubilities?

Thanks
John
 
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  • #2
Nope you're thinking too hard. If it is ionic in general it is soluble in polar solvents.

Now there is a cutoff. A 500000 dalton hydrocarbon polymer with a single charged group is obviously not going to be soluble. Where is the cutoff? Hard to say.

That requires computational chemistry.
 

1. What is the difference between sodium benzoate and toluene?

Sodium benzoate and toluene are two different chemical compounds. Sodium benzoate is a salt derived from benzoic acid, while toluene is an aromatic hydrocarbon. They have different chemical structures and properties, and are used for different purposes.

2. Which one is more soluble in water, sodium benzoate or toluene?

Sodium benzoate is more soluble in water than toluene. This is because sodium benzoate is a polar compound, meaning it has a slight positive and negative charge, which allows it to interact with water molecules and dissolve. Toluene, on the other hand, is nonpolar and does not interact with water, making it insoluble.

3. How is solubility determined in these two compounds?

Solubility is determined by the interactions between the solute (sodium benzoate or toluene) and the solvent (water). In the case of sodium benzoate, it has polar molecules that can form hydrogen bonds with water, making it soluble. Toluene, being nonpolar, cannot form these bonds and therefore is insoluble in water.

4. Can the solubility of these compounds be affected by temperature?

Yes, the solubility of both sodium benzoate and toluene can be affected by temperature. In general, the solubility of solids in liquids increases with increasing temperature, while the solubility of gases in liquids decreases with increasing temperature. This is due to the changes in molecular motion and interactions at different temperatures.

5. What factors can affect the solubility of sodium benzoate and toluene?

Aside from temperature, other factors that can affect the solubility of these compounds include the polarity of the solvent, pressure, and the presence of other substances. For example, adding a polar solvent like ethanol can increase the solubility of toluene, as it can interact with both the toluene and water molecules. On the other hand, adding a nonpolar substance like oil can decrease the solubility of sodium benzoate, as it can compete with water molecules for interactions with the sodium benzoate.

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