Chemistry - Is sodium chloride really odourless? If yes, what do I smell?
Solution 1:
Since odour is generally coming from vapour / gas form of a material, and NaCl has zero vapour pressure, it should be odourless. However:
Moving around solid materials, dust, small particles can fly around that can be dissolved in the nose and interact with the odour sensors.
You almost always have something else together with salt. And if it is not pure, you cannot be sure what makes the odour, the salt or the impurity. Eg. sea salt often contains remains of algae.
Solution 2:
Your table salt is not just $\ce{NaCl}$; there are countless other compounds which make up the table salt.
Here are a few:
- $\ce{NaCl}$ - the main component
- Iodine in the form of $\ce{I-}$ and $\ce{IO_3^-}$ salts (salts of potassium and sodium usually).
- Iodine Stabilizers: $\ce{I2}$ sublimes at room temperature; therefore, stabilizers are added to prevent the loss of iodine. A commonly used stabilizer is dextrose.
- Iron is added in the form of ferrous fumarate.
- Folic acid and other vital vitamins are also added.
- Fluoride salts are also added in many countries.
- Anti-caking agents such as $\ce{Na4[Fe(CN)6]}$, $\ce{CaCO3}$, $\ce{MgCO3}$, $\ce{Ca3(PO4)2}$ and fatty acids are added.
From the big list above, fatty acids usually have an odor. While solids have a negligible vapor pressure, some molecules do leave the surface. Therefore, you can still smell solids.
The main component of the sea smell is dimethyl sulphide ($\ce{CH3-S-CH3)}$. In the ocean, dimethyl sulphide is produced as a byproduct by the bacteria which decompose phytoplankton.
The manufacturer of the common salt you use might be using sea water as the raw material. The sea water might not have been thoroughly cleaned which could have left traces of compounds found in sea water in your salt. You might want to try buying salt manufactured by a different company.