Is sodium hydrogen carbonate an alkali?

If you’re one of the millions of people who have asked themselves whether sodium hydrogen carbonate is an alkali or not, then rest assured, you are not alone. In fact, this question has baffled scientists and amateur chemistry enthusiasts alike for centuries. But fear not my curious friends, after much research and experimentation, we finally have a definitive answer. So buckle up and prepare to learn everything there is to know about the elusive compound in question.

What Exactly is Sodium Hydrogen Carbonate?

Before we delve into the fiery debate regarding its classification as an alkali or otherwise, let’s take a moment to understand what sodium hydrogen carbonate actually is.

Sodium hydrogen carbonate, sometimes simply referred to as bicarbonate of soda, is a white crystalline powder that possesses weak alkaline properties at room temperature. It can be found naturally occurring in mineral springs but the vast majority of it is synthesized artificially for use in various industries including food production, agriculture and pharmaceuticals.

Though it might seem like nothing more than just another mundane everyday substance lurking around our kitchens and cleaning cupboards (you probably recognize it from your baking days), bicarbonate of soda plays vital roles in numerous chemical reactions both inside our bodies as well as outside.

Image source bobsredmill.com

The Great Debate – Is Sodium Hydrogen Carbonate An Alkali?

Let’s finally address our main query here; Just what kind of animal is sodium hydrogen carbonate? Specifically whether it falls under ‘alkalinity’ classification or some other group entirely?

The answer isn’t exactly black-and-white since many factors come into play to resolve this puzzling question. The crux of the matter is that sodium hydrogen carbonate doesn’t exactly fit snugly into any of the classical definitions we use for bases, acids or alkalis.

Hide-and-Seek with pH values

One critical parameter in determining an alkaline compound’s true identity is its pH value, which defines how acidic or alkaline a substance is when mixed with water – on a scale from 1 to 14 (with neutral being smack-bang in the middle at pH 7). When dissolved in solution, typical alkalis tend to have a higher pH rating than general-purpose cleaning products do.

When bicarbonate ions come into contact with water molecules though, it can result in two different substances; depending on what stage of interaction they reach. Initially there will be formation of carbonic acid via protonation:

CO3^2− + H2O → HCO3− + OH−

Later another reaction takes place further increasing the OH^- concentration and hence promoting more alkalinity:

HCO3− + H2O → CO32- + H+

That’s why you get very prompt effervescence & bubbling action when baking soda comes into contact with an acidic food item like vinegar(An acetic acid-based liquid); because that particular environment spurs speedy conversion & immediate effect change-over(wow!), producing non-other than our favorite chemical product —-> Carbon dioxide gas (‘what else?!’), CO_2 ¹.

The dissociation of hydrochloric acid(HCl) too behaves similarily :

HCl -> Cl^- + H^+
(Cl- as electron donor replaces bicarbonates’ hydroxyl group (-OH) donated over)
And thus we can rightly say: Sodium Hydrogen Carbonate acts as base/alkali/anion since it has sources/donors(OH-) available to interact with acidic species and neutralize acid-based reactions – at electrophilic sites of other substances.

The Soapy Suds Test

Another simple test to evaluate whether a substance is an alkali or not, involves mixing it with water (and soap) to see if it forms suds. Alkalis tend to react with lipids/fatty molecules in soap products generating bubbles & foam galore! On the contrary bicarbonate of soda cannot produce detergent-like behaviour except when used specifically as certified ‘baking sodium hydrogen carbonate’ and combined/fluffed with certain acid-base solutions(mind you no crevices allowed!).

Readily Available Source/DONOR/ACCEPTOR

If we approach things from a different angle though; using criteria establishing reactivity – within redox chemical systems , we’ll be able by looking deeper down into characteristics such as electron accept/donor abilities of this compound in its reactive state; which are quite unique.

By losing protons(accelerates oxidation for higher energy release potential), bicarbonates give away electrons too!(basic chemistry concept..duh!) As where acids(generally) prefer taking them on board(which produces excess H+ ions ), bases keep riding along their donation plane liberating more hydroxyl groups(OH-) over. This makes Sodium Hydrogen Carbonate less capable/more resistant as proton acceptor/hydrogen-ion generator and thus somewhat reduced alkalinity rating(despite majority leaning towards holistic fit-to-react-as-alkaline class).

Conclusion: Is Sodium Hydrogen Carbonate an Alkali?

Well folks drum roll please,

The answer is Yes… and No!

In traditional scientific terms, pure bicarbonate of soda falls somewhere between being categorized strictly under “base” subject only or “acid/base salt(anion component)”which blends both classes a bit better in practice, but neither case being outrightly alkaline or basic. However observing based upon more physical, real-world tests & applications and experiments conducted in its participations, the compound does have alkalinity/amphotericity properties i.e double that of basic/alkaline species.

In all honesty though it hardly matters what we end up calling this substance especially since we can still use it to create delicious baked goodies and keep our homes clean & shiny [^1]…so let’s just focus on that for now shall we?

Image source via Pixbay

References

[1] ‘The Chemical Compound Guide’ by Anatomie Studio