Research Gate and their team of Scientist have contributed to Dr. Kantor’s Understanding Alkalinity and Acidity research publication. See the additions on version 2.0 below.
UNDERSTANDING ALKALINITY AND ACIDITY
By Dr. Keith David Kantor
1 – THE BASICS
1.1 – The Problem
The body is remarkably adept at maintaining a blood pH between 7.35 and 7.45. Just as blood pH operates within a certain range, so do other cell structures throughout the body, depending on what kind they are and to which system they belong. This cellular pH can affect both the structure and chemical reactivity of cellular molecules.
Water is the universal solvent for all life and its chemical properties affect how cells work. Beyond this, water’s self-ionization plays a role in providing the hydrogen protons needed for certain cellular processes. Even though the dissociation constant of water is incredibly small, its importance is very large because of the reactive nature of hydrogen protons in biological systems. Hydrogen protons have profound effects on metabolism and other cell processes disproportionate to their relatively small number resulting from water’s self-ionization.
The body has a series of natural buffers which help the blood and cells resist changes in pH. These include hemoglobin in the red blood cells, plasma proteins, the bicarbonate buffer, and the phosphate buffer. But buffering does not eliminate acidity, rather it merely neutralizes it with an opposite charge. Neutralization through buffering and neutralization through elimination are not the same. For this reason, these natural buffers are able to maintain the pH level but fail to remove the acidic overload (excess hydrogen protons) modern life imposes on the body. They will keep the cell and blood pH within a set range but acidic conditions can still affect the body even within these ranges. Stressors come both from without and within the body. What we do as individuals, or more accurately what we consume, plays an enormous role in how the body can withstand both the pressures from outside as well as inside the body. Acidity (excess hydrogen protons) leads to inflammation which in turn can lead to many other health problems.
1.2 – The Nature of Water
In order to understand what happens within the body, one must first understand the nature of water because the body consists of more than 60% water. Generally, blood is 92% water, the brain and muscles are 75% water, and bones are about 22% water. At its very core, the body is an aqueous environment so an understanding of water will lay the foundation upon which alkalinity and acidity can be understood.
A water molecule consists of one oxygen atom and two hydrogen atoms held together by a covalent bond. A covalent bond is a chemical bond in which atoms share electron pairs. The water molecule is also a polar molecule with an electrical dipole moment. This means it has both a positive and a negative side or pole. Water as a substance can form a large number of intermolecular hydrogen bonds, which results in the tendency of water molecules to clump together. All of these factors lead to the strong attractive forces water exhibits and make water a good polar solvent. In fact, water is a universal solvent, meaning substances dissolve in water (lose their chemical integrity) rather than water losing its chemical integrity. This, however, is just the beginning.
Even pure water consists of more than just water molecules. Through a process called self-ionization, two different ions are formed from water molecules. When one water molecule donates a hydrogen proton to another water molecule two new ions are formed. The first is called hydroxide (OH–), a negative ion (anion) that is formed by the water molecule that donates one of its hydrogen protons. The second is called hydronium (H3O+), a positive ion (cation) that is formed by the second water molecule when it accepts the donated hydrogen proton. The hydroxide then becomes a hydrogen proton acceptor because it wants to return to being a water molecule and hydronium becomes a hydrogen proton donor for the same reason. These ions exist in very small amounts in the overall aqueous solution and usually for short durations but they do play an important role in water and in the biology of the body. These ions occur because water has an amphiprotic nature, meaning it can act as both an acid and a base. This then is the power of water; it can transform itself to suit its environment and always seeks to maintain an equilibrium between the positive and the negative.
1.3 – The Nature of Ions
In order to understand the acid/alkaline (acid/base) relationship we must first look at basic chemistry and the electro-magnetism involved. Atoms in their natural state exist in balance, with the number of protons which are positively charged matching the number of electrons which are negatively charged. When an imbalance in this equilibrium happens, the atom becomes an ion. If it has more protons than electrons, then it is a positively charged ion called a cation. If it has more electrons than protons, then it is a negatively charged ion called an anion. In most instances only the word ion is used to refer to both cations and anions. The same rules apply to molecules and the same naming system. Therefore an ion can either be an atom or a molecule that is imbalanced and has a charge.
Ions play a major role in the acid/base reaction. The first modern definition describes how acids and bases interact in an aqueous solution (water). Simply put the Arrhenius theory maintains that:
An acid is any substance that produces hydrogen ions in an aqueous solution.
A base is any substance that produces hydroxide ions in an aqueous solution.
The hydrogen ions form through the dissociation of the acid and the hydroxide ions form by the ionizing of the base. Bases are said to ionize because they can either dissociate or dissolve whereas acids almost uniformly dissociate. In both instances, it is the action of water as a universal solvent that sets the ions free. For all practical purposes the concept of dissociation and dissolution have the same effect of freeing ions in an aqueous solution.
A hydrogen ion and a hydrogen proton are the same thing because hydrogen is the simplest atom, with one proton and one electron. When the hydrogen proton exists without its electron, it is an ion or cation to be more precise. Throughout this article, hydrogen proton or just proton will be used to designate the hydrogen ion.
The Arrhenius theory was limited in its scope because it only dealt with acids and bases in aqueous solutions and only looked at the relationship between hydrogen ions and hydroxide ions. In an attempt to solve some of the limits of the Arrhenius theory, a new theory emerged put forth separately by two different individuals and became known as the Brønsted-Lowry theory, named for both of them. The Brønsted-Lowry theory holds that:
Acids are proton donors.
Bases are proton acceptors.
The proton in question is the hydrogen proton (hydrogen ion). Acids have at least one hydrogen proton that they easily transfer to another substance through a process called deprotonation. Furthermore, since bases are proton acceptors, they are in fact acceptors of hydrogen protons and this is called protonation. This concept of hydrogen proton donation and acceptance is fundamental to understanding how alkaline waters work.
The Arrhenius theory gives us the foundation of hydrogen ions and hydroxide ions and the Brønsted-Lowry theory gives us the concept of hydrogen proton transfer. With these theories as our basis, we can now discuss the fundamental chemistry behind base aqueous solutions, aka alkaline waters, and acidic aqueous solutions.
1.4 – The Nature of Hydroxide
Up to this point we have been discussing the hydroxide ion as if it exists in large quantities in water by itself. But hydroxide is not normally found by itself in nature, rather it is attached to another element, most commonly a metal (mineral) to form a base molecule or compound. The strongest bases in terms of alkalinity in an aqueous solution are the hydroxides formed from the alkali metals and the alkaline earth metals.
It is important to note that pH and alkalinity do not measure the same properties. Potential hydrogen (pH) measures the acid or base properties of a substance while alkalinity measures the quantitative ability of a base to neutralize an acid. Remember, neutralization of an acid is not necessarily the same as the elimination of an acid. This will be discussed in detail later on.
The first issue is the structure of the two groups of hydroxides. Alkali metal hydroxides are monovalent and alkaline earth metal hydroxides are divalent. This means for every one mineral ion in an alkali metal hydroxide there is only one corresponding hydroxide ion but in alkaline earth metal hydroxides there are two hydroxide ions for every mineral ion. Simply put, alkaline earth metal hydroxides contain twice as many hydroxide ions as alkali metal hydroxides.
The next issue is ionization in an aqueous solution that frees the hydroxide ion. The term ionization is used because it can come about either through dissociation or dissolution. As noted earlier, the concepts of dissociation and dissolution have the same effect of freeing ions in an aqueous solution. According to Arrhenius, free hydroxide ions are the most important factor in determining alkalinity in an aqueous solution.
Among the alkali metal hydroxides, potassium and sodium are the strongest in terms of alkalinity in an aqueous solution. Both completely dissociate in water. This means that the mineral ions (either sodium or potassium) and the hydroxide ions break apart and float freely in the water. Potassium hydroxide is slightly stronger than sodium hydroxide.
Among the alkaline earth metal hydroxides, calcium and magnesium are the strongest in terms of alkalinity in an aqueous solution. Calcium hydroxide is not quite as strong a base as potassium hydroxide or sodium hydroxide because it is only relatively soluble where the other two completely dissociate. To reach a saturated solution of calcium hydroxide, an equal amount of undissolved calcium hydroxide must be present in relation to the calcium ions and hydroxide ions freely floating in the solution. So for every two free hydroxide ions there is one corresponding calcium ion and one corresponding calcium hydroxide molecule.
Magnesium hydroxide, on the other hand, is even weaker because it has low solubility and does not dissociate very well. Even though this is true, magnesium hydroxide is still used as a common component of antacids because even with its weaker properties it is still effective.
Potassium hydroxide, sodium hydroxide, calcium hydroxide, and magnesium hydroxide are all strong bases with strong alkalinity in an aqueous solution. Magnesium hydroxide is by far the weakest of the four because of its solubility and dissociation issues. The other three each produce effective levels of free hydroxides in an aqueous solution.
1.5 – The Nature of Hydronium
As with the hydroxide ion, the hydrogen proton does not exist as its own entity in an aqueous solution in any large amount. The hydrogen proton always wants to be attached to another atom or molecule that has electrons it can share. This seems somewhat at odds with the definition of an acid being a hydrogen proton donor but it is nonetheless true. The hydrogen proton may easily leave an acid but it then seeks to attach itself to another atom or molecule.
This is where the properties of water step in. As noted, water can act as an acid or a base and is a universal solvent. According to Arrhenius and later affirmed by Brønsted-Lowry, an acid dissociates in an aqueous solution because of the solvent properties of water. The freed hydrogen proton then attaches to a water molecule just as happens in water self-ionization. The new molecule is hydronium (H3O+, a positive ion or cation). But hydronium does not actually exist in water by itself either. Here the clumping properties of water due to hydrogen bonding come into play and hydronium is usually found attached to other water molecules so you end up with hydronium ion/water molecule clusters or complexes.
One well known example is H3O+(H2O)6 and shows a hydronium ion attached to six water molecules. This cluster is the mean hydration ion in cold water. A second example is H3O+(H2O)20 and shows a hydronium ion attached to 20 water molecules. This is called the magic ion number structure because of its increased stability. Two other examples are the Zundel cation and Eigen cation found in the Grotthuss mechanism. These are H5O2+ and H9O4+, respectively. The first shows a hydronium ion attached to one water molecule and the second shows a hydronium ion attached to three water molecules.
By its very nature, hydronium is the most acidic species that can exist in water. The logic is simple. An acid stronger than hydronium will by its very nature deprotonate (donate a proton) through dissociation in an aqueous solution. Deprotonation is the very definition of a strong acid. The result will be a protonated water molecule, aka hydronium. A weaker acid is by definition weaker than hydronium. Hydronium formed in acidic solutions is longer lasting and more concentrated than hydronium that forms through the self-ionization process in water.
The nature of water, the nature of ions, the nature of hydroxide, and the nature of hydronium are the fundamental chemistry needed to understand how acids and bases exist and react in an aqueous solution.
2 – THE BATTLE
2.1 – Overview
How does the knowledge set forth above apply in the real world? What is the best way to arm the body to handle the acidic load modern life produces both from without and within?
First let’s define exactly what the enemy is, so that we can then figure out how to defeat it. It is clear that since hydronium is the most acidic species that can exist in an aqueous solution and that the body is by its very nature an aqueous environment, hydronium necessarily becomes the most important acid to combat in the body. Other acids may be present but they naturally convert to hydronium through dissociation. Excess hydrogen protons in the form of hydronium is the real problem. The extra hydrogen proton in hydronium is still highly reactive and like all acids, hydronium will donate it to another atom or molecule freely under the right circumstances. This is what makes hydronium so potentially harmful to the human body. First, because hydronium ties up free water molecules it changes the hydration parameters of the body. Second, although the hydrogen proton may be attached to a water molecule, it is basically free to act as if it is a free ion since acids by definition are proton donors. This potential reactivity of the extra hydrogen proton can be combatted by neutralization.
2.2 – Neutralization
As noted earlier, alkalinity is a measure of the quantitative ability of a base to neutralize an acid. There are two basic methods of neutralization, buffering through addition of alkaline substances and elimination through transformation. The most common method of neutralization is the addition of an alkaline substance that provides a negative charge to counter the positive charge of the hydrogen proton. This is the basis of most of the buffering systems found in the body. This is also the basis of most alkaline waters. In alkaline waters this is accomplished by the addition of alkaline minerals, trace minerals, or electrolytes. But the addition of an alkaline substance does not remove the acidity, rather it merely counters it with an opposite charge. In this case the aqueous solution becomes pH neutral but the troublesome hydrogen proton in the form of hydronium still remains.
The other form of neutralization is elimination by transformation. When hydroxide ions come into contact with hydrogen protons they combine and form new water molecules. Here is the basic formula:
OH– + H+ → H2O
This transformation of the hydrogen proton and hydroxide ion into a new water molecule neutralizes the acid because a water molecule is neutral. Further it removes the hydrogen proton from the aqueous solution and in fact increases the aqueous solution. The next section will look more closely at the role of hydroxide as an acid fighter.
2.3 – Hydroxide – The Champion Acid Fighter
As noted in section 1.4 above, potassium hydroxide, sodium hydroxide, calcium hydroxide, and magnesium hydroxide all have strong alkalinity in an aqueous solution. These four are the most prevalent hydroxides found in alkaline waters and will therefore be the focus of this discussion. Of these, potassium hydroxide, sodium hydroxide, and calcium hydroxide produce the highest degree of free hydroxide ions in an aqueous solution.
According to the Arrhenius theory, the hydroxide ion readily combines with the hydrogen proton to form water and thus neutralize the acidic nature of the hydrogen proton. Arrhenius goes further and states that hydrogen protons freely dissociate from their acids in aqueous solutions much like the hydroxide ions from potassium hydroxide, sodium hydroxide, and calcium hydroxide do. At this point it is important to reiterate that the hydrogen proton does not actually exist as a free species in an aqueous solution but combines with a water molecule to form hydronium. So in reality a hydroxide ion combines with a hydronium ion to form two new water molecules. The chemical equation is this:
OH– + H3O+ → H2O + H2O
Furthermore, the hydroxide ion itself has a low solubility and therefore does not break apart easily. By its very nature as part of the water molecule structure, it has an inherent drive to return to its natural state as a water molecule. This then is the power of the hydroxide ion.
These facts lead to a very simple question, how do you supply the most possible free hydroxide ions in an alkaline water? Several factors play into answering this question. As noted, both potassium hydroxide and sodium hydroxide are monovalent which means they have one hydroxide ion for every mineral ion. Calcium hydroxide and magnesium hydroxide, on the other hand, are divalent so they have two hydroxide ions for every mineral ion. The simple math would support the idea then that the calcium and magnesium hydroxides must provide more free hydroxide ions but this is misleading. As noted, magnesium hydroxide has a very low solubility, so it does not produce many free hydroxide ions. Calcium hydroxide is relatively soluble except when in the presence of potassium hydroxide or sodium hydroxide, then its solubility decreases rapidly. This means if an alkaline water is using many different minerals in its ionization process to create its hydroxide, the potassium and sodium hydroxides would produce the highest degree of free hydroxide ions and the calcium hydroxide would be inhibited from doing so. It also means more minerals are necessary because of their monovalent properties.
2.4 – Electro-Magnetically Induced Ionization
In sections 1.3 and 1.4 above, the term ionization was used to describe the process by which the hydroxide ion is freed from its mineral ion partner through either dissociation or dissolution. In this section ionization will refer to the process by which the hydroxide ion is removed from a water molecule. Both processes are forms of ionization but in the first one the hydroxide ion is separated from a mineral ion and in this section the hydroxide ion is separated from a hydrogen proton.
Most alkaline waters on the market today recognize the fact that minerals alone cannot effectively combat acidity. Although most alkaline waters rely mostly on added minerals, they also seek to give the body more potent ammunition. In most cases this ammunition comes in the form of negative ions. Although most may not say so, the negative ions are in fact hydroxide.
Most of the leading alkaline waters on the market today claim they have or add negative ions. The question is how do they do this? They use the same technology that alkalinizing water machines use. Both the ready to drink alkaline waters in the store and the alkaline water machines sold for home use employ the same basic technology. It is important to note at this point that although each of these may claim that their technology is different or special or even patented, the simple fact is they all use the same basic principles. In order to create hydroxide they all apply electro-magnetism to break apart the water molecule into hydroxide ions and hydrogen protons. Although they all uniformly use the term hydrogen proton, as noted earlier, a free hydrogen proton will immediately attach to any molecule with which it can share an electron. Since other water molecules are within reach, the newly freed hydrogen proton will protonate one of these water molecules and form the hydronium ion. This electro-magnetism is applied in the presence of minerals, most notably sodium, potassium, calcium, and magnesium among others. The mineral hydroxide rich water produced in this process is the alkaline water product and the acid rich hydrogen (hydronium) water is discarded or used for other purposes. This basic method for producing negative ions is used by both ready to drink alkaline waters and alkaline water machines for home use.
Since this is the way most of the industry creates negative ions (hydroxide), is this the only way to do it? The short answer is no. In most alkaline waters, the free hydroxide ions available are limited by the amount of minerals present because of the reasons noted in section 2.3. But does this always have to be the case? The simple answer is no.
3 – A DIFFERENT METHOD
3.1 – Hydroxide Rich Water Approach
As noted in section 2.2, most alkaline waters use the addition of alkaline minerals, trace minerals, or electrolytes as the basis of their alkalinity and therefore their approach to combatting acidity. This means buffering rather than elimination is the main method of neutralization. To bolster the buffering capabilities of these minerals, most alkaline waters also undergo ionization as discussed in section 2.4. This forms hydroxide which is necessarily limited by this method of production. Because most alkaline waters see addition of minerals as the most important tool and hydroxide as only a secondary tool, their ability to take advantage of the acid eliminating potential of hydroxide is limited.
A far better approach is to seek to increase the amount of free hydroxide ions available because these neutralize excess acid by elimination rather than just buffering as demonstrated in section 2.3. The best way to increase free hydroxide ions is to add hydroxide from natural sources to the water rather than creating them through electromagnetically induced ionization. Sodium hydroxide, potassium hydroxide, and calcium hydroxide are the best candidates to provide the most free hydroxide ions in an aqueous solution. Historically, sodium hydroxide and potassium hydroxide were both produced by combining calcium hydroxide with either sodium carbonate (soda ash) or potassium carbonate (potash), respectively. Today they are manufactured through easier, cheaper processes. Calcium hydroxide, on the other hand, is still created from calcium carbonate (limestone) through the introduction of heat and then water. All three of these are good sources of free hydroxide ions but each has different strengths and weaknesses.
As noted in section 1.4, both sodium hydroxide and potassium hydroxide are monovalent. This means they only have one hydroxide ion for each mineral ion. Calcium hydroxide, on the other hand, is divalent meaning it has two hydroxide ions for each mineral ion. Calcium hydroxide, therefore, has the potential to have twice as many hydroxide ions available for the same amount of mineral content as the other two.
Also noted in section 1.4, both sodium hydroxide and potassium hydroxide almost completely dissociate in an aqueous solution which means the hydroxide ions and the minerals ions break apart almost completely. Calcium hydroxide is relatively soluble so its ions do not break apart completely like the others do. Calcium hydroxide will break apart at a rate of about 50%. This means for every two free hydroxide ions there will be one calcium ion and one calcium hydroxide molecule.
Any of these three when added to water will provide an abundance of free hydroxide ions. Each can also be naturally processed to remove much of the mineral content while concentrating the free hydroxide ion content through precipitation and other means. The water then becomes a hydroxide rich water rather than just an alkaline water. Hydroxide rich water by its very nature is a far stronger acid fighter than alkaline waters that rely chiefly on minerals for their alkalinity. Combatting acidity by transforming excess hydrogen protons back into water molecules eliminates the acidity rather than just countering it by buffering. Elimination through transformation reduces the acidic load while also providing hydration. This hydration can then be used by the body or easily removed through normal channels.
3.2 – A Practical Application
The role of lactic acid in muscle fatigue during exercise has fallen under much scrutiny in recent times. Current research and theory holds that it is a buildup of hydrogen ions in the muscles that is to blame. Whether these hydrogen ions come from dissociation from lactic acid or are created during the break down of ATP, is still a matter of debate. The fact that the acidity associated with the presence of these hydrogen ions is the cause of muscle fatigue is now almost universally accepted. As noted throughout this article, hydrogen ions do not exist as a distinct species in an aqueous solution, so the real culprit is hydronium. As has already been established, hydroxide would be the best, most natural solution to help the body deal with this buildup. This makes hydroxide rich water with its high concentration of free hydroxide ions uniquely qualified to help solve the problem of exercise induced hydrogen ion (hydronium) buildup in the muscles.
The free hydroxide ions from hydroxide rich water are readily available for the body to use to help maintain the acid-base balance in any cell or system in the body. When a hydrogen ion dissociates from an acid or is otherwise produced as a by-product of some other chemical reaction, it attaches to a water molecule and turns it from H2O into H3O, the hydronium ion. When hydroxide comes into contact with the hydronium, it combines and two new water molecules are formed. As noted earlier, the chemical equation is this:
H3O+ + OH– → H2O + H2O
The free hydroxide ions that hydroxide rich water provides the body, work seamlessly within the biological mechanisms the body already uses to maintain its acid-base balance. Because the end product is water, balance is restored, inflammation is reduced, hydration is enhanced, and detoxification is bolstered.
4 – CONCLUSION
4.1 – The Source Matters
Most alkaline waters focus first and foremost on adding minerals to increase alkalinity. They then use electromagnetically induced ionization to create negative ions, aka hydroxide. This process, by its very nature, limits the amount of free hydroxide ions that can be produced and utilized. Adding naturally sourced mineral hydroxides provides far more hydroxide ions than electromagnetically induced ionization can. Naturally sourced mineral hydroxides also allow for the concentration of free hydroxide ions and the minimization of mineral ions. By focusing on the hydroxide and not the minerals, it is possible to create a hydroxide rich water. Alkalinity based on hydroxide content is far more effective in combatting acidity than alkalinity based on mineral content.
4.2 – The Method of Neutralization Matters
When mineral content is the focus of a water’s alkalinity then buffering is the main method of neutralization. Buffering rebalances pH but it does not eliminate acidity. The hydrogen protons are still there to disrupt the body’s biology. When hydroxide content is the focus of a water then acid elimination through transformation is the main method of neutralization. Concentrating the free hydroxide ions while minimizing the mineral content increases the acid eliminating capabilities of the water. Hydroxide ions neutralize acidity by transforming the acid back into water that can then be used for hydration or detoxification. Neutralization through transformation eliminates the acid completely and removes its disruptive effects on the body’s biological systems. Buffering merely stabilizes the pH but cannot stop the disruptive effects of the presence of excess acidity.
- 1.1 Properties of Water
- 2.6 Regulation of Intracellular Hydrogen Ion Concentration
2.6.1 Importance of Intracellular [H+]
2.6.2 ‘Intracellular Buffering’
- MAINTAINING CELLULAR CONDITIONS: pH AND BUFFERS
- Brønsted–Lowry acid–base theory
- Alkalinity Table (hydroxides and carbonates)
Source: Marx, D.; Chandra, A; Tuckerman, M.E. (2010). “Aqueous Basic Solutions: Hydroxide Solvation, Structural Diffusion, and Comparison to the Hydrated Proton”. Chem. Rev. 110 (4): 2174–2216.
- Calcium hydroxide
- Sodium hydroxide
- Potassium hydroxide
- Acid Base Reactions
- Lactic Acid/Lactate