- What is pH?
- What is the pH scale?
- What is a logarithic measure?
- What is the normal pH for my body?
- How does a change in pH affect my body?
- What is Acidosis?
- What causes an acid imbalance in the body?
- How do excess acids impact my health?
- How is my weight affected by excess acids?
- What does drinking high alkaline water do to my health?
pH is a logarithmic measure of ion concentration, originally defined by
Danish biochemist Soren Peter Lauritz Sorensen in 1909. In short, it is a measure
of the acidity or alkalinity of a solution. The lower the
pH number, the more acidic is the substance. The higher the number, the more
alkaline it is.
| Representative pH Values |
| Substance |
pH |
| Hydrochloric acid, 10M |
-1.0 |
| Lead-acid battery |
0.5 |
| Gastric acid |
1.5 -2.0 |
| Lemon juice |
2.4 |
| Cola |
2.5 |
| Vinegar |
2.9 |
| Orange or apple juice |
3.5 |
| Tomato juice |
4.0 |
| Beer |
4.5 |
| Acid rain |
<5.0 |
| Coffee |
5.0 |
| Tea or healthy skin |
5.5 |
| Urine |
6.0 |
| Milk |
6.5 |
| Pure water |
7.0 |
| Healthy human saliva |
6.5 - 7.4 |
| Blood |
7.34 - 7.45 |
| Seawater |
7.7 - 8.3 |
| Hand soap |
9.0 - 10.0 |
| Household ammonia |
11.5 |
| Bleach |
12.5 |
| Household lye |
13.5 |
The name, pH, has claimed to have come from any of several sources
including:
|
pondus hydrogenii |
|
|
potentia hydrogenii
|
(Latin) |
|
potentiel hydrogene
|
(French) |
|
potential of hyrdogen
|
(English) |
According to the Compact Oxford English Dictionary, the "p"
stands for the German word for "power," potenz, and pH therefore is
an abbreviation for "power of hydrogen."
Despite its origins, it is generally agreed that
the term
pH is the short form for
potential of hydrogen. The pH of any solution
is the measure of the hydrogen-ion concentration. It is
the number that arises
from a measure of the activity of hydrogen ions
(or their equivalent) in the solution.
The important thing to understand about pH is how it relates to oxygen.
The higher the pH reading, the more
alkaline and hydrogen rich the fluid is.
The lower the pH reading,
the more acidic and hydrogen
deprived is the fluid.
The pH scale is considered to range
from 0 to 14,
with 0 being extremely acidic and 14 being extremely basic, or alkaline. As the pH
scale is logarithmic, it doesn't start at zero.
While most substances have a pH in the range of 0 to 14, extremely acidic
or extremely alkaline substances may have a pH less than 0 or greater than 14.
An example is acid mine runoff, with a pH of of -3.6.
The most acidic of liquids encountered can have a pH as low as -5. The most alkaline
typically have a pH of 14.
|
Neutral pH at 25 ºC is not exactly 7.0. pH is an experimental value,
so it has an associated error. Since the dissociation of water is
(1.011 ± 0.005) x 10-14, pH of water at 25 ºC would be 6.998 ± 0.001.
The value is consistent, however, with neutral pH being 7.00 to two
significant figures, which is near enough form most people to assume
that it is exactly 7. |
When water has a pH level of 7.0 at room temperature (25 ºC), it is defined
as "neutral."
Water with a pH less than 7.0 is considered
acidic, while water with a pH greater than 7.0 is considered basic, or
alkaline. However, the neutral pH is different for each solvent. For
example, ethanol is neutral at pH 9.8. A solution with a pH of 8 would be considered
acidic in ethanol but alkaline in water.
The pH of water gets smaller with higher temperatures. For example,
the pH of water at 50 ºC is 6.55 ± 0.01. This means that a diluted solution
is neutral at 50 ºC when its pH is around 6.55 and that a pH of 7.00 is
basic, or alkaline.
Additionally, when pure water (water with pH of 7.0) is exposed to the
atmosphere, it will take in carbon dioxide. Some of this carbon dioxide
reacts with water
to form carbonic acid and hydrogen protons, thereby lowering the pH to about 5.7.
The pH scale is an inverse logarithmic representation of hydrogen proton (H+)
concentration developed in 1909 by Peter Sorensen.
Unlike linear scales which have a constant relations between the
item being measured (H+ concentration in this case) and the value reported,
each individual pH unit is a factor of 10 different than the next higher or lower
unit.
The pH scale was defined because of the enormous range of hydrogen ion concentrations found
in aqueous solutions make using the H+ molarity awkward. For example, in a typical
acid-base titration, [H+] may vary from about 0.01 M to 0.0000000000001 M. It is
easier to write "the pH varies from 2 to 13."
Thus, each individual pH unit is a factor of 10 different than the next higher or lower
unit For example, if any substance changes from pH 7 to pH 8, it has become
ten times more alkaline. If the substance changes from pH 7 to pH 6, it
has become ten times more acidic. A shift from 2 to 4 represents a
one-hundred-fold (10 × 10) decrease in hydrogen proton concentration.
The pH varies with different parts of the body. For example, blood pH
must remain about 7.4 while the stomach
pH value is maintained around 4. The inside of the stomach is acidic in order to
digest food and kill the kinds of bacteria and viruses
that come with food.
In an ideally functioning body, the first morning's saliva would register at pH 6.5-6.75,
urine at 6.5-6.8, and venous blood at 7.3-7.35. Each day our bodies diligently strive to
achieve and maintain those pH balances.
Blood is always slightly alkaline. Or at least it should be. A normal healthy body has an almost equal blood pH of acidity
and alkalinity. The most ideal pH balance is 7.365, which means the
body is slighty more alkaline than acidic.
Your blood is
the only transport system for nutrients to every part of your body.
Your body can effectively
assimilate vitamins, minerals, and food supplements only when the
pH level is in balance.
Your blood,
therefore, cannot afford to be acidic. It needs to stay within a
pH range that will maintain resistance to decay or
putrefaction, and growth of malevolent organisms.
Your blood pH has a very narrow range of
around 7.35 to 7.45. If your body's pH deviates from this range,
you will be sick or have symptoms of illness. If your blood pH exceeds 7.45, the
condition is called alkalosis. Alkalosis refers to a condition reducing
hydrogen ion concetration of arterial blood plasma. The main cause of respiratory acidosis
is hyperventilation, resulting in loss of carbon dioxide. Metabolic alkalosis can be
caused by prolonged vomitting, resulting in a loss of hydrochoric acid with the
stomach content.
If your arterial blood plasma pH falls below 7.45, the
condition is called acidosis. Acidosis is an increased acidity (i.e.
an increased hydrogen ion concentration). If not further qualified, it refers
to acidity of blood plasma. Respiratory acidosis results from a build-up of
carbon dioxide in the blood due to hyperventilation. Metabolic acidosis is an
increased production of metabolic acids. Metabolic acidosis is usually compensated for
in the lungs, as increased exhalation of carbon dioxide promptly shifts the
buffering equation to reduce metabolic acid.
Changes in the pH of arterial blood outside this range
result in irreversible cell damage. If your blood pH
falls below 6.8 or rises above 7.8, your body cells will stop
functioning and you will lapse into a coma and die.
The body therefore does everything it can to maintain this pH balance.
Excess acidity
forces the body to borrow minerals—including sodium, calcium, potassium, and
magnesium (which are alkaline)—from vital organs and bones to buffer (neutralize)
the acid and safely remove it from the body.
