Baking Soda pH: A Weak Base

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The pH of baking soda is approximately 9. Baking soda, or sodium carbonate (sometimes referred to as sodium hydrogen carbonate), is a common chemical base with a number of different uses. What’s the chemical composition of baking soda, and how does baking soda’s properties as a chemical base make it useful for so many different household applications?

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The Properties Of Baking Soda

The fact that baking soda is a chemical base means that when it comes into contact with acid it makes the carbon dioxide within the acid free. It’s this attribute that makes it a useful baking implement. Baking soda’s stability means that it is noncombustible (it lacks a flash point where it actually catches fire), though it does have a melting point of around 60 degrees Celsius (100 degrees Fahrenheit). Baking soda lacks a boiling point as well, though it begins to decompose around 70 degrees Celsius or 158 degrees Fahrenheit.

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Baking soda is used to leaven food when making things like fried foods, pastries, and pancakes. Its use as a leaven-er helps foods hold their shape when they lack the ability to do so themselves, like when batter can’t hold its form long enough for the yeast to rise in it. Acidic foods will react with baking soda and create gas bubbles, which will cause batter containing baking soda to rise. The batter just has to be heated for a while and then the gas bubbles that expanded during the baking soda’s reaction will cement into place.

Batter that contains baking soda will actually rise slowly by itself if it just sits at room temperature. The batter’s acid and the bases in the baking soda will react, just not as quickly as they will when in an oven. Heat causes the batter to rise much faster because it degrades the baking soda at a faster rate, releasing more gas.

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There are many other uses for baking soda including cleaning your home and keeping your fridge smelling nice. Baking soda is an excellent absorber of odor and moisture, so it can be put in your fridge to absorb the smell of pungent food products (such as fish). Baking soda is also useful as a cleaning implement. You can use baking soda to clean dirty surfaces like counters and stoves. Baking soda can also break down mold and mildew. To clean surfaces with baking soda, simply combine the baking soda with some vinegar and then use it to clean the surface. The dirtiest spots should be cleaned up first.

Baking soda is also useful when cleaning up urine stains from pets, to freshen your laundry, or as a toothpaste. When cleaning up accidents from pets, use vinegar and warm water on the spot first then apply some baking soda to the spot afterward. To use baking soda to remove the smell of sweat or other odors from laundry, use one or two cups of baking soda alongside your normal detergent.

Chemical Formula

Baking soda’s chemical formula is NaHCO3. So baking soda is composed to one atom of sodium, an atom of hydrogen, an atom of carbon, and three oxygen atoms. This chemical formula makes the compound very stable.

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Baking soda is a chemical base, with a pH value of between 9 to 9.5 on the ph scale.
Baking soda’s density is approximately 2.159 g/cm3, and it is water-soluble. The water solubility of baking soda is around 8 grams for every hundred grams of H2O.

The pH Scale: What Does A pH of 9 Mean?

What does a pH of value of 8.1 – 8.4 mean exactly? What is the pH scale? The pH scale is a ranking of “hydrogen potential” and it is used to compare the relative acidity or basicity (alkalinity) of one substance to another substance. The pH scale is logarithmic, so every whole number change in pH is equivalent to a change of times 10 the previous number on the scale. The scale is centered at pH 7, neutral ph – neither an acid or a base. Pure water is said to be a neutral 7 pH.

The number of hydrogen ions found within pure water is approximately equal to 1 x 10^-7 M. The M refers to the numbers of moles per liter in the water. Note that the pH of most water is not 7. Most collections of water are filled with minerals and other compounds. Distilled water is essentially pure water, but as soon as you open a container of distilled water it will contact the air, begin dissolving carbon dioxide, and become more acidic, attaining a pH of around 6.

An acidic solution is a solution that has hydrogen ion concentrations higher than water, while basic solutions (also called alkaline solutions) are those which have concentrations of hydrogen ions lower than water’s concentration of hydrogen ions. In other words:

Acid = H+ concentration > 1 x 10^-7 M
Base = H+ concentration < 1 x 10^-7 M

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A basic solution tends to raise the pH value of other solutions when combined together. This happens because basic solutions introduce hydroxide to the environment, and hydroxide binds with free hydrogen ions, removing them from the environment. In contrast, substances that are acidic in nature usually increase the concentration of hydrogen ions when introduced to another substance. This is because acids dissociate/degrade and release hydrogen atoms into the substance. Stronger acids degrade faster and end up releasing more H+ into the environment of the solution, while stronger bases release more hydroxide ions.

So if you say that baking soda has a pH value of around 8.1, you’re saying baking soda is slightly more basic than pure water. It’s a mildly alkaline substance, more basic than both neutral water and weaker bases like sea water (which has a pH of 8). Yet baking soda is far less basic than something like milk of magnesia, ammonia, or lye.

In comparison, acidic substances are things like blood (pH of approx. 7.2), coffee (pH of approx. 4.8), Milk (pH of about 6.5), and distilled vinegar (pH of around 2.5).

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Opinions expressed are solely the authors and do not express the views or opinions of Science Trends nor the author's institution.
Cite this article as:
Daniel Nelson, MS. Baking Soda pH: A Weak Base, Science Trends, 2018. Available at:
http://doi.org/10.31988/SciTrends.22582
*Note, DOIs are registered Friday weekly and therefore may not work until then.

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