It is a unit of measurement of alkalinity or acidity of a solution, more specifically the pH measures the amount of hydrogen ions that a certain solution contains, the meaning of pH in its acronym is potential of hydrogen ions, this has become a practical way to handle alkalinity figures, instead of other slightly more complicated methods. It can be measured precisely through the use of a tool known as a pH meter, this device can measure the potential difference between a pair of electrolytes.
What is pH
Table of Contents
The concept of pH is a parameter that is used to measure the degree of acidity of a substance. Through this it is possible to determine the concentration of hydrogen ions (positive hydrogen ion) in a solution.
The hydrogen ion potential of a solution can be measured with approximations, using for them indicators of acids or bases which can present a different color depending on the level of alkalinity or acidity, normally the method consists of using a paper impregnated with the indicators qualitative. Other indicators used are methyl orange and phenolphthalein.
In chemistry the determination of acidity or alkalinity of a substance is one of the most important procedures, since through the results of this one can obtain a lot of data regarding the structure and activity of the molecules and in turn know more with relative to the cells of the body.
The definition of hydrogen ions potential is basically the acids and bases that have different concentrations of hydrogen ions, the strongest being those that contain the greatest amount of ions and the weakest being those that do not have such a concentration. This is in charge of expressing the numerical value of the concentrations of hydrogen ions.
In some cases, the ion charge is usually quite low, which becomes tedious when working with these figures, which is why a unique table was devised, called the " pH scale ", the table is composed of 14 numbered units, from 0 to 14, with 0 being the maximum acidity point and 14 the maximum base, 7 represents the midpoint of the table and is neutral, which means that solutions with a value below 7 are acidic and those above are basic.
What is pH for
The pH serves to determine the alkalinity or acidity of a substance and determines the measure of concentration of hydrogen ions.
The pH scale
The hydrogen ion potential scale was created by Soren Peter Lauritz Sorensen (1868-1939), a Danish biochemist born in Haure Bjerg, in 1901 he was appointed as director of the Chemical Section of Carlsberg Laboratories, since then he became one from leading researchers on amino acids, enzymes, and proteins.
The concentration of hydrogen ions (protons) played a key role in enzymatic reactions, so in 1909 he devised a simple way to express it, which was to calculate the negative logarithm of said concentration. In this way, simple and manageable values were obtained within a convenient scale, which he called pH.
The hydrogen ion potential scale is numbered from 1 to 14, between 1 and 6 means that the substance is more acidic, 7 is the case of distilled water and has a neutral value, and 8 to 14 means that the substance is more alkaline.
The sequence that the pH scale has is logarithmic, which means that the difference between one numerical unit and another can be 10 times more basic or acidic depending on the case.
The values on the pH scale are multiplied by 10 in each unit. That is, the hydrogen potential value of 6 is 10 times more acidic than a pH with a value of 7, but a hydrogen potential of 5 is 100 times more acidic than a pH of 7.
Another case is the hydrogen potential value of 8 which is 10 times more alkaline than a pH with a value of 7, but a hydrogen potential of 9 is 100 times more alkaline than a pH of 7.
Importance of pH in everyday life
The man in his day to day uses many chemicals that could be dangerous, it is for this reason that a pH measurement must be carried out, to test their degree of acidity and the risk that can be run when using them.
Eating food alters the body's pH. The stomach of a person has a pH of 1-4 since this acid is necessary for the decomposition of food. Some foods can cause the stomach to generate more acid, this is very common and this acid can perforate the walls of the stomach and cause ulcers. Its excess could reach the esophagus, reach the mouth and cause what is commonly known as heartburn, so the quality of the food consumed must be taken care of.
There are vegetables such as cherry, strawberry, purple cabbage, onion and purple cabbage, which contain a substance called anthocyanin, this is very sensitive to the values of potential hydrogen ions. In the specific case of purple cabbage, it has cyanidin, which can be used as an indicator that changes color when exposed to a chemical substance.
In the case of the potential for hydrogen ions in the mouth after brushing your teeth, its value is normally around 7, that is, a neutral pH, which does not cause any damage to the teeth. If the pH is below 5.5, the enamel begins to lose, damaging the teeth. To reduce this in the gums and teeth, a healthy mouth must be maintained; brushing is necessary after every meal.
pH of some substances that are part of people's daily lives:
- Example substance - pH level
- Hydrochloric acid 1 M - 0
- Gastric juice - 1
- Lemon juice - 2
- Vinegar - between 2.4 and 3.4
- Orange juice - 4
- Beer - 5
- Milk - 6
- Pure water - 7
- Blood - 8
- Soapy water - 9
- Milk of Magnesia - 10
- Lime water - 11
- Ammonia - 12
- 0.1 M sodium hydroxide - 13
- 1M sodium hydroxide - 14
PH indicators
The pH indicators are the different means that are used to determine the hydrogen ion potential of a substance. There are three types that are, liquid indicators, indicator papers and pH meters.
Liquid indicators
They are organic bases that have different colors that vary according to their acid form. They work in limited ranges, vary their color and stop varying when it reaches the maximum level of that range. It should be used only in colorless solutions, to be able to observe the color change.
There are a large number of liquid indicators of different ranges of hydrogen ions potential, and colors, including cresol red (red to yellow in a range of 0.2 to 1.8), methyl red (red to yellow in a range of 0.2 to 1.8). range 4.2 to 6.2), bromocresol green (pink to blue / green 4.2 to 5.2), and phenolphthalein (colorless to pink in a range 8.0 to 10.0).
These indicators are widely used in analytical chemistry degrees, but you must have a level of training to make this practice accurate.
pH meters
These arise from the need of laboratories and their analysts, to obtain exact values from this parameter, something that is not achieved with liquid indicators, or those of paper. It is based on the measurement of the electric potential differential between the pH of the electrode and the reference electrode.
This equipment consists of two electrodes, one of which is metallic and insensitive to the pH of the solution, plus a simple electronic amplifier. Its calibration is carried out with solutions of known pH, which are used to read substances.
Indicator papers
It is a litmus paper (it is made with a powder from lichens) that must come into contact with the solution in a discreet way, in order to analyze and measure its precision.
This paper is used to know if a liquid or gaseous solution is basic or acidic, its presentation is in two colors, red and blue.
When it comes to a liquid solution, the paper should not be completely inserted into it, the process is to drop drops or touch the liquid in a very brief way.
When the solution is gaseous, the gas must be passed over the paper surface, so that in this way it changes color.
urine pH
Urine is made up of solid and liquid elements. In pathological processes in the body, the kidneys may eliminate not only typical substances (substances that the kidneys normally excrete in the urine), but also other components of metabolism.
The hydrogen ions potential of urine is obtained through analyzes carried out on samples of this substance. This analysis is carried out using a test strip made of a pad with a color scale. The color that the strip takes is the meaning of pH or the acid that the urine contains.
Normal urine values range from 4.6 to 8.0 in pH, when these levels are altered, it can signify a real or urinary tract disorder.
water pH
As noted above, the potential for hydrogen ions indicates when a substance is alkaline or acidic, this is one of the most common tests applied to water to know its quality. There are different types of water and each one has its own pH values, these are:
- Distilled water: Its pH is 5.8
- Drinking water, its hydrogen ion potential is between 6.5 and 9.5
- The mineral water the pH is between 4.5 and 9.5
- Ocean water maintains an alkaline hydrogen ion potential with values between 7.4 and 8.5
- Aquarium water can have life if it maintains its hydrogen ion potential between 4.5 and 9, although these levels are considered extreme, an aquarium can maintain a neutral pH between 6.8 and 7.2.
- The potential for hydrogen ions in swimming pool water must maintain a pH between 7.2 and 7.6, above these values, chlorine loses its effectiveness and below these levels the water would be very acidic for the body of bathers, causing irritation to skin and eyes.
milk pH
Milk is considered one of the most complete foods in nutrition for humans. Due to its varied composition (proteins, carbohydrates, fats, vitamins and mineral salts), due to its high digestibility and its capacity for use by the human body, its taste and its possibilities of use in the preparation of other food products, liquid milk and dairy products, being essential foods to satisfy the biological needs of the human being.
To measure the real acidity of milk and determine its pH, a portable meter model HI 98162 is used, which consists of an electrode to measure the alkalinity or acidity level of the milk.
Generally, the hydrogen ion potential of milk is around 6.7, when this value begins to fall, it becomes acidic and the degradation of this product begins, generating bacteria that produce lactic acids, breaking lactose and lowering the pH of the milk.
blood pH
In humans, the balance of the pH of the blood is essential, a variation in these levels can cause a coma and even death. This type of potential hydrogen ions should be slightly alkaline at a level between 7.35 and 7.45, but studies show that 90% of the inhabitants of developed countries suffer from acidosis.
Acidosis is directly related to people's diet, habits, pollution, and emotional health. Acidity alters the optimal levels of electrolytes in the body at a chemical and elemental level, acts on the electrolytes of Sodium, Iron, Potassium, Calcium and each of these have a vital, fundamental and specific function in the body.
saliva pH
The Saliva is a body fluid compound by 99% and the remainder are inorganic and organic molecular, this comes from the salivary glands.
The normal hydrogen ion potential of saliva should be between 5.6 to 7 and is composed of ions such as sodium, potassium or chlorine and enzymes that contribute to the initial breakdown of food, protection against bacterial infections, healing and taste functions.
soil pH
The pH of the soil, its degree of acidity or alkalinity, is measured through the potential scale of hydrogen ions, generally soils maintain a pH between 4 and 8, despite this most of the crops thrive on land with values between 6 and 7.
In soils with a potential for hydrogen ions less than 6.5, the availability of phosphorus and molybdenum is notably reduced. Those with a pH higher than that figure (tending to alkaline) reduce the availability of copper, manganese, zinc and iron.
vinegar pH
Vinegar is a liquid substance that is used as a condiment for food, but apart from this it has other qualities for which it can be used. Its pH is between 2.4 and 3.4. The acidity of vinegar is volatile, and this is due to the presence of acetic acid.
skin pH
For a potential of hydrogen ions of the face and body to be in optimal conditions, they must be between the levels of 4.7 5.755, this means that the pH in the skin is slightly acidic. This can vary slightly according to the area of the body and the gender of the person, they also intervene in the different stages of life.
The pH table
The pH table measures the degree of acidity of an object. Objects that are not very acidic are called basic. This table has values ranging from zero (the most acidic value) to 14 (the most basic). An example is pure water which has a pH value of 7. This value is considered neutral, neither acidic nor basic.
Normal clean rain has a pH value between 5.0 and 5.5, a slightly acidic level. However, when rain combines with nitrogen oxides and sulfur dioxide, produced by power plants and cars, the rain becomes much more acidic. Typical acid rain has a pH value of 4.0. A decrease in pH values from 5.0 to 4.0 means that the acidity is ten times higher.
PH meters
Hydrogen ion potential meters are instruments that are used to measure the alkalinity and acidity of substances. These measurements are represented by a scale that goes from 0 to 14.
How is pH measured?
To measure the hydrogen ion potential of a substance, it can be done by two methods, the potentiometric or the colorimetric.
The colorimetric is the simplest method, substances known as indicators of potential of hydrogen ions are used that exist in different presentations and with specific properties to measure the determined pH levels.
