Did you know that sodium is an alkali metal like lithium and potassium?
Is it also “evil,” i.e., explosive, like potassium in water?
Yes. Yes it is.
Like its companions on the periodic table, sodium is too reactive to exist by itself in nature. It forms compounds, some of which are incredibly useful to us.
5. Sodium keeps you clean
The small print on a soap or shampoo label looks like a chemistry textbook. If you study it, you’ll notice that most of the chemicals at the top of the list contain sodium.
Because of their ionic chemistry, both potassium and sodium make terrific soap (oddly enough, the same chemistry makes lithium an excellent lubricant). Sodium is used more often than potassium in commercial soap making because it’s less expensive than potassium and makes a harder product.
But soaps are only the beginning of sodium’s role in cleaning.
Sodium carbonate, also known as washing soda or soda ash, is a water softener and stain remover. It will also remove scale in coffee pots and espresso boilers. In toothpaste (where you might also find sodium fluoride), sodium carbonate acts as a foaming agent and abrasive. It also temporarily reduces your mouth’s pH.
Sodium bicarbonate, a/k/a baking soda, is used in laundry detergent and toothpaste, too. It’s also the “soda” that was used to soda-blast all the crud off the Statue of Liberty back in the 1990s. At home, you can just make a paste of it for cleaning.
Lye – sodium hydroxide – has been used in soap making for centuries. It also reacts with acidic gases like sulfur dioxide, which makes it an excellent industrial air scrubber. As caustic soda, sodium hydroxide is frequently used as an industrial cleaner, and of course, we use it in the home for cleaning ovens and opening up drains.
Household bleach is a weak solution of sodium hypochlorite and sodium hydroxide. It’s used in disinfectant sprays and wipes. Stronger solutions are used to disinfect water meant for public use. Sodium hypochlorite is also used in toilet cleaners.
4. Industrial and agricultural uses for sodium
We think of sodium in terms of table salt – sodium chloride – but it forms other salts, too. This makes it a valuable industrial material.
This isn’t to say that sodium chloride doesn’t have industrial uses. It’s widely used in the food industry, for instance. As rock salt, NaCl is also extensively used for deicing.
We saw up above that sodium carbonate – Na2CO3 – is useful in cleaning and personal care products, but it’s mainly used for glass making. It acts as a flux, lowering silica’s melting temperature. Sodium carbonate is also a strong base, and it is used to regulate acidity in a wide range of industrial processes.
Sodium hydroxide, as lye or caustic soda – NaOH to you chemists – is another strong industrial base. It’s especially useful in cleaning parts or tanks, paint stripping and processing forest products.
Bicarbonate of soda, with a chemical formula of NaHCO3, is used in some fire extinguishers, particularly in commercial kitchens. It forms a flame-smothering foamy soap upon contact with hot grease or when it mixes with the acid that’s also supplied in the extinguisher.
Sodium nitrate – NaNO3 – is sometimes called Chile saltpeter. Because it contains nitrogen, sodium nitrate is widely used as an agricultural fertilizer, as well as in manufacturing explosives ranging from gunpowder to solid rocket propellant.
Sodium hypochlorite – NaClO, also known as bleach – oxidizes toxic cyanide waste into a nontoxic cyanate.
Bleach keeps down microbes in industrial water systems. Photographers also it to regulate pH when they are processing film.
3. Sodium cools down your car
Your car’s engine is probably the last place you would expect to find sodium, but it might be in there to cool down the valves.
Liquid sodium can move (PDF) a lot of heat. This makes it useful in some types of nuclear reactor.
2. Sodium in food
“Too much” is the first thing that comes to mind when talking about sodium in food. We’ll look at that issue next. For now, let’s look at why sodium is used in cooking and food processing.
It’s a great preservative because it inhibits the growth of bacteria. In fact, until canning and refrigeration came along, people used sodium compounds for food preservation. Salt is still used today for pickling and jerky.
Sodium nitrate is also used to preserve food, especially cured meats. Just to make things confusing, sodium nitrite is a preservative, too, mainly for deli meats.
Health concerns have been raised about the nitrogen compounds from both of these sodium compounds – nitrate and nitrite – but so far no definite risk has been clearly established.
Sodium bicarbonate, a/k/a baking soda, has a lot of uses in cooking, of course.
Its primary use is to lighten the texture of foods like pancakes and cookies. This leavening happens when it releases CO2 while mixed together with a weak acid like vinegar or buttermilk and heated.
Sodium bicarbonate also tenderizes meat and vegetables
Lybil BER
Sodium carbonate is used as an acid regulator in food. It also adds flavor to Chinese steamed buns and noodles and conditions the crust of Cantonese moon cakes.
This sodium compound is also a leavening agent like baking soda, and it keeps food dry enough not to clump together.
Sodium hydroxide – lye – is mostly used for industrial food treatments such as cleaning raw vegetables, processing cocoa, or thickening ice cream.
However, dipping pretzels in a very dilute lye solution just before baking gives them that special crust and flavor. Sodium hydroxide treatment also brings us hominy, lutefisk, and other specialty foods.
Here’s how it works for hominy. The “ash” mentioned is wood ash from which sodium carbonate was extracted. Today, they use lye to make hominy commercially. Apparently you can also use baking soda, although I wonder how good that hominy is.
Mmmm…pozole!
Note that the hominy is rinsed thoroughly before cooking. The only dietary sodium in this dish is what you and the cook put into it.
1. Sodium and your body
As we saw last week, living cells need the sodium-potassium pump to survive. Remember this?
As you can see, this transport process leaves more sodium outside the cell than inside it.
Good old Na+ is the most common electrolyte in extracellular fluid. It serves the vitally important function of holding water there so some wonderful things can happen.
In human beings, complex metabolic functions maintain the fine balance of water and sodium that keeps you alive and healthy. Basically, the amount of sodium you ingest each day should equal the amount your kidneys clean out of your system.
WHO recommends (PDF) that adults take in 2 g (about 1 teaspoon) of sodium per day. More than that can give you health problems. Too little dietary sodium can also make you very sick.
Balance is the key word when it comes to your sodium intake, just as it is for your body. So, go easy with that salt shaker – but don’t toss it away.
Sodium isn’t really evil. It improves our lives by keeping us clean and healthy, maintaining our industrialized world, and bringing us plenty of clean, delicious foods.
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More information:
- Sodium. Its elemental
- Regulation of Na+ balance. University of Washington, Conjoint 401-403
- Sodium bicarbonate. Wikipedia
- Sodium carbonate. Wikipedia
- Sodium hydroxide. Wikipedia
- Sodium hypochlorite. Wikipedia
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