Why Doesn't CO2 Dissolve Ionic Compounds?

In summary, CO2's nonpolar nature is due to its molecular geometry, despite having partially charged carbon and oxygen atoms. This prevents it from dissolving ionic molecules like NaCl, even though polar molecules are known to do so. The strong repulsion from the carbon atom's positive charge is not enough to overcome the strong bonds in NaCl. However, supercritical CO2 can be used as a solvent.
  • #1
alingy1
325
0
So, CO2 is said to be non polar because of its molecular geometry.
However the carbon atom has two positive charges and the oxygens, one partial charge each.
Therefore, why doesn't CO2 dissolve ionic molecules like NaCl? We've been taught that a polar molecule is one that can separate ionic compounds. Any close Na+ ion would be attracted to the carbon atoms, no?
 
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  • #2
Sure - get close enough to any particular atom and you'll see it's charge; but how close would you have to get?

You pretty much answer your question in your preamble - it's because of the geometry of the molecule.

In your description, the C is 2+ ... so wouldn't the Na+ get repelled?
The attraction/repulsion has to be strong enough to tear the NaCl apart.

But note: supercritical CO2 is used as a solvent.
 

FAQ: Why Doesn't CO2 Dissolve Ionic Compounds?

Why is carbon dioxide not a liquid solvent?

Carbon dioxide (CO2) is not a liquid solvent because it exists as a gas at standard temperature and pressure. In order for a substance to act as a solvent, it must be able to dissolve other substances in a liquid state. CO2 does not have the necessary properties to dissolve other substances in a liquid form.

Can carbon dioxide dissolve any substances?

Yes, carbon dioxide is able to dissolve some substances, but only at high pressures and low temperatures. At these conditions, CO2 can act as a solvent for certain solutes, such as some organic compounds and salts. However, this is not a common or practical use of CO2 as a solvent.

How does carbon dioxide compare to other solvents?

Carbon dioxide has different properties compared to other commonly used solvents, such as water and ethanol. For example, it has a lower boiling point and does not have the ability to form hydrogen bonds, which are important for dissolving polar solutes. This makes it less effective as a solvent in many cases.

Why is carbon dioxide sometimes referred to as a "green solvent"?

Carbon dioxide is sometimes referred to as a "green solvent" because it is non-toxic and non-flammable, making it a safer alternative to traditional organic solvents. Additionally, CO2 is a naturally occurring substance and can be easily captured and recycled, reducing its impact on the environment.

Is carbon dioxide a good solvent for all chemicals?

No, carbon dioxide is not a good solvent for all chemicals. As mentioned before, it has limited solubility for certain solutes, particularly polar substances. It also has limited ability to dissolve ionic compounds, which are often highly soluble in water. Therefore, CO2 may not be the best choice of solvent for all chemical reactions and processes.

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