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You are watching: Is table salt a pure substance


When we think salt, we think of the compound Sodium Chloride. However, common table salt contains much more than just good old NaCl. Knowing that, is table salt a compound, mixture, or solution?

Table salt is a mixture because it contains additives to prevent clumping, as well as various supplements to improve health. Substances commonly found in table salt include not only sodium chloride (NaCl) but sodium ferrocyanide (Na4Fe(CN)6) and potassium iodide (KI).

This article details what is found in regular table salt, as well as speaking about a few others. It also explains the difference between compounds, mixtures, and solutions and whether any of salt’s ingredients are bad for your health.


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What Is Table Salt?

Everyday table salt is 97-99% sodium chloride (NaCl). However, it also contains an anti-caking agent, as well as some healthy add-ons.

Anti-Caking Agents

The most common anti-caking agent is sodium ferrocyanide (Na4Fe(CN)6), also known as yellow prussiate of soda. It absorbs oil and water, preventing the salt from sticking together into a clump. Despite the “cyanide” in the name, it is a harmless substance, approved multiple times for use in food.

Iodine

Table salt also contains some form of iodine to prevent iodine deficiency, which causes thyroid problems. Some common forms of iodine are potassium iodide (KI), sodium iodide (NaI), or sodium iodate (NaIO3). Potassium iodide and sodium iodide, in particular, suit salt well, as their white or colorless crystals mix well with the NaCl.

Non-iodized salt is available for pickling purposes as well as for people preparing to undergo radioactive iodine treatment for their thyroid cancer. The first form of iodine has been used since 1924.

In short, most table salts contain a mix of at least three distinct substances, not dissolved in each other in any way.

Other Table Salts

Kosher salt is designed to most effectively remove blood from meat, by Jewish tradition. It contains no iodine or additives except for the usual anti-caking compound.Sea salt is evaporated from the ocean and so contains many minerals found in water. Potassium, iron, zinc can all be found in sea salt.Fleur de Sel is less of a salt and more of a spice: it is harvested from the top of saltwater ponds in Brittany and contains more minerals. It is considered a delicacy.In Europe, salt sometimes contains fluoride to prevent cavities.
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The Difference Between Compounds, Solutions, and Mixtures

Compounds

A compound is a uniform substance containing one type of molecule made out of two or more elements. An example would be water (H2O). Its molecules are made out of two elements, hydrogen and oxygen, and all its molecules are the same, like this:

H2O H2O H2O

H2O H2O H2O

H2O H2O H2O

An example of something that is not a compound would be steel: steel is made out of iron molecules, carbon molecules and contains traces of manganese, silicon, phosphorus, sulfur, and oxygen. Therefore, its molecules will be different, like this:

FeO FeO FeO CO FeO

MnO FeO FeO P2O5 FeO

FeO SiO2 FeO FeO CO

Pure salt (NaCl) is a compound, but since table salt contains more than NaCl, we do not count it as one.

Mixtures

A mixture is made out of two or more physically combined substances. “Physically combined” here means mixed together without a chemical reaction. An example of a mixture would be sand and salt together. Two different substances, made out of different molecules, mixed into one.



Homogenous mixtures

Mixtures come in two different forms, homogenous and heterogenous. A homogenous mixture has the two substances spread evenly through it so that there is no clear line between the two. An example of a homogeneous mixture would be salt and sugar.

Heterogenous mixtures

A heterogeneous mixture has a clear line between the two substances. Think of oil and water mixed together: the oil floats to the top, separating itself from the water in a clear boundary.

Table salt is a mixture because it contains at least three substances. Salt contains NaCl molecules, as well as sodium ferrocyanide (Na4Fe(CN)6), and either potassium iodide (KI), sodium iodide (NaI), or sodium iodate (NaIO3). We can even go one step further and classify salt as a homogenous mixture because there is no obvious separation between its ingredients.

Solutions

A solution is a homogeneous mixture in which one substance is dissolved in another. “Dissolve” here means that the molecules of the solute (the substance being dissolved) must break apart into their ions. For example, salt dissolves in water, and the end result is a solution. If you look closely, you will find that floating around in the water are not molecules of NaCl, but individual Na+ and Cl- ions, like this:

H2O Na+ H2O Cl- H2O

H2O Cl- H2O Na+ H2O

H2O Na+ H2O Cl- H2O

Solutions are usually thought of as liquid, but solid and gaseous solutions exist.

In table salt, the additives must remain whole to work. The anti-caking agent won’t be able to do its job if it is split into Na+ and Fe(CN)64- ions. Therefore, they cannot be considered “dissolved”, and table salt cannot be considered a solution.

Are Any of the Substances in Salt Dangerous?



All of the ingredients in salt are there for a reason, and all of them have been approved for consumption. If you still prefer to avoid the additives, there are many versions of salt which have them removed, such as non-iodized salt or kosher varieties.

Salt itself shouldn’t be eaten too often: high salt intake has been linked to higher rates of stomach cancer. However, this is no reason to go on a salt-free diet. Low salt consumption can result in high cholesterol, heart disease, and insulin resistance.

Conclusion

Table salt is a homogeneous mixture. It has more than one substance, physically combined so that you cannot tell the fractions apart.

It is not a compound because it contains more than one substance. Likewise, it is not a solution because for an ionic solid to be considered a solution, one of the ionic substances must break its bonds and dissolve. Dissolving any substances found in table salt would render them useless.

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Additives in table salt are nothing to be afraid of: they are there to ensure good health and add more interest to the mixture to modern table salt.