What is the reaction of the liquid medium with ph 0. The acidity of the medium. The concept of the pH of the solution. pH values in solutions of different acidity
The tissues of a living organism are very sensitive to fluctuations in pH - outside the permissible range, proteins are denatured: cells are destroyed, enzymes lose their ability to perform their functions, death of the organism is possible
What is pH (hydrogen index) and acid-base balance
The ratio of acid and alkali in any solution is called acid-base balance.(ABR), although physiologists believe that it is more correct to call this ratio the acid-base state.
KShchr is characterized by a special indicator pH(power Hydrogen - "power of hydrogen"), which shows the number of hydrogen atoms in a given solution. At a pH of 7.0, one speaks of a neutral medium.
The lower the pH level, the more acidic the environment (from 6.9 to O).
An alkaline environment has a high pH level (from 7.1 to 14.0).
The human body is 70% water, so water is one of its most important constituents. T atea person has a certain acid-base ratio, characterized by pH (hydrogen) index.
The pH value depends on the ratio between positively charged ions (forming an acidic environment) and negatively charged ions (forming an alkaline environment).
The body constantly strives to balance this ratio, maintaining a strictly defined pH level. When the balance is disturbed, many serious diseases can occur.
Keep the right pH balance for good health
The body is able to properly absorb and store minerals and nutrients only at the proper level of acid-base balance. The tissues of a living organism are very sensitive to fluctuations in pH - outside the permissible range, proteins are denatured: cells are destroyed, enzymes lose their ability to perform their functions, and the body may die. Therefore, the acid-base balance in the body is tightly regulated.
Our body uses hydrochloric acid to break down food. In the process of vital activity of the body, both acidic and alkaline decay products are required., and the first is formed more than the second. Therefore, the body's defense systems, which ensure the invariance of its ASC, are "tuned" primarily to neutralize and excrete, first of all, acidic decay products.
Blood has a slightly alkaline reaction: The pH of arterial blood is 7.4, and that of venous blood is 7.35 (due to excess CO2).
A pH shift of at least 0.1 can lead to severe pathology.
With a shift in blood pH by 0.2, a coma develops, by 0.3, a person dies.
The body has different levels of PH
Saliva - predominantly alkaline reaction (pH fluctuation 6.0 - 7.9)
Typically, the acidity of mixed human saliva is 6.8–7.4 pH, but at a high rate of salivation it reaches 7.8 pH. The acidity of the saliva of the parotid glands is 5.81 pH, the submandibular glands - 6.39 pH. In children, the average acidity of mixed saliva is 7.32 pH, in adults - 6.40 pH (Rimarchuk G.V. and others). The acid-base balance of saliva, in turn, is determined by a similar balance in the blood, which nourishes the salivary glands.
Esophagus - Normal acidity in the esophagus is 6.0–7.0 pH.
Liver - the reaction of cystic bile is close to neutral (pH 6.5 - 6.8), the reaction of hepatic bile is alkaline (pH 7.3 - 8.2)
Stomach - sharply acidic (at the height of digestion pH 1.8 - 3.0)
The maximum theoretically possible acidity in the stomach is 0.86 pH, which corresponds to acid production of 160 mmol/l. The minimum theoretically possible acidity in the stomach is 8.3 pH, which corresponds to the acidity of a saturated solution of HCO 3 - ions. Normal acidity in the lumen of the body of the stomach on an empty stomach is 1.5-2.0 pH. The acidity on the surface of the epithelial layer facing the lumen of the stomach is 1.5–2.0 pH. Acidity in the depth of the epithelial layer of the stomach is about 7.0 pH. Normal acidity in the antrum of the stomach is 1.3–7.4 pH.
It is a common misconception that the main problem for a person is the increased acidity of the stomach. From her heartburn and ulcers.
In fact, a much bigger problem is the low acidity of the stomach, which occurs many times more often.
The main cause of heartburn in 95% is not an excess, but a lack of hydrochloric acid in the stomach.
The lack of hydrochloric acid creates ideal conditions for the colonization of the intestinal tract by various bacteria, protozoa and worms.
The insidiousness of the situation is that the low acidity of the stomach "behaves quietly" and goes unnoticed by a person.
Here is a list of signs that make it possible to suspect a decrease in stomach acid.
- Discomfort in stomach after eating.
- Nausea after taking medication.
- Flatulence in the small intestine.
- Loose stools or constipation.
- Undigested food particles in the stool.
- Itching around the anus.
- Multiple food allergies.
- Dysbacteriosis or candidiasis.
- Dilated blood vessels on the cheeks and nose.
- Acne.
- Weak, peeling nails.
- Anemia due to poor absorption of iron.
Of course, an accurate diagnosis of low acidity requires determining the pH of gastric juice.(for this you need to contact a gastroenterologist).
When acidity is increased, there are a lot of drugs to reduce it.
In the case of low acidity, there are very few effective remedies.
As a rule, preparations of hydrochloric acid or vegetable bitterness are used, stimulating the separation of gastric juice (wormwood, calamus, peppermint, fennel, etc.).
Pancreas - pancreatic juice is slightly alkaline (pH 7.5 - 8.0)
Small intestine - alkaline (pH 8.0)
Normal acidity in the duodenal bulb is 5.6–7.9 pH. The acidity in the jejunum and ileum is neutral or slightly alkaline and ranges from 7 to 8 pH. The acidity of the juice of the small intestine is 7.2–7.5 pH. With increased secretion, it reaches 8.6 pH. The acidity of the secretion of the duodenal glands - from pH 7 to 8 pH.
Large intestine - slightly acidic (5.8 - 6.5 pH)
This is a weakly acidic environment, which is maintained by normal microflora, in particular, bifidobacteria, lactobacilli and propionobacteria due to the fact that they neutralize alkaline metabolic products and produce their acidic metabolites - lactic acid and other organic acids. By producing organic acids and lowering the pH of the intestinal contents, the normal microflora creates conditions under which pathogenic and opportunistic microorganisms cannot multiply. That is why streptococci, staphylococci, klebsiella, clostridia fungi and other “bad” bacteria make up only 1% of the entire intestinal microflora of a healthy person.
Urine - predominantly slightly acidic (pH 4.5-8)
When eating with animal proteins containing sulfur and phosphorus, acid urine is mainly excreted (pH less than 5); in the final urine there is a significant amount of inorganic sulfates and phosphates. If the food is mainly dairy or vegetable, then the urine tends to be alkalized (pH over 7). The renal tubules play a significant role in maintaining acid-base balance. Acidic urine will be excreted in all conditions leading to metabolic or respiratory acidosis as the kidneys compensate for shifts in acid-base balance.
Skin - slightly acid reaction (pH 4-6)
If the skin is prone to oiliness, the pH value may approach 5.5. And if the skin is very dry, the pH can be as high as 4.4.
The bactericidal property of the skin, which gives it the ability to resist microbial invasion, is due to the acid reaction of keratin, the peculiar chemical composition of sebum and sweat, and the presence of a protective water-lipid mantle with a high concentration of hydrogen ions on its surface. The low molecular weight fatty acids included in its composition, primarily glycophospholipids and free fatty acids, have a bacteriostatic effect that is selective for pathogenic microorganisms.
Sex organs
The normal acidity of a woman's vagina ranges from 3.8 to 4.4 pH and averages between 4.0 and 4.2 pH.
At birth, a girl's vagina is sterile. Then, within a few days, it is populated by a variety of bacteria, mainly staphylococci, streptococci, anaerobes (that is, bacteria that do not require oxygen to live). Before the onset of menstruation, the acidity level (pH) of the vagina is close to neutral (7.0). But during puberty, the walls of the vagina thicken (under the influence of estrogen - one of the female sex hormones), the pH drops to 4.4 (i.e., the acidity increases), which causes changes in the vaginal flora.
The uterine cavity is normally sterile, and lactobacilli that inhabit the vagina and maintain the high acidity of its environment prevent the entry of pathogens into it. If for some reason the acidity of the vagina shifts towards alkaline, the number of lactobacilli drops sharply, and in their place other microbes develop that can enter the uterus and lead to inflammation, and then to problems with pregnancy.
Sperm
The normal level of semen acidity is between 7.2 and 8.0 pH. An increase in the pH level of sperm occurs during an infectious process. A sharply alkaline reaction of sperm (acidity of about 9.0–10.0 pH) indicates a pathology of the prostate gland. With blockage of the excretory ducts of both seminal vesicles, an acid reaction of sperm is noted (acidity 6.0-6.8 pH). The fertilizing ability of such sperm is reduced. In an acidic environment, spermatozoa lose their mobility and die. If the acidity of the seminal fluid becomes less than 6.0 pH, the spermatozoa completely lose their mobility and die.
Cells and interstitial fluid
In the cells of the body, the pH value is about 7, in the extracellular fluid - 7.4. Nerve endings that are outside the cells are very sensitive to changes in pH. With mechanical or thermal damage to tissues, the cell walls are destroyed and their contents enter the nerve endings. As a result, the person feels pain.
Scandinavian researcher Olaf Lindal did the following experiment: using a special needleless injector, a very thin stream of a solution was injected through the skin of a person, which did not damage the cells, but acted on the nerve endings. It was shown that it is hydrogen cations that cause pain, and with a decrease in the pH of the solution, the pain intensifies.
Similarly, a solution of formic acid directly "acts on the nerves", which is injected under the skin by stinging insects or nettles. The different pH values of tissues also explain why a person feels pain in some inflammations, and not in others.
Interestingly, injecting pure water under the skin caused particularly severe pain. This phenomenon, strange at first glance, is explained as follows: cells, upon contact with pure water, rupture as a result of osmotic pressure and their contents act on the nerve endings.
Table 1. Hydrogen indicators for solutions
|
Solution |
RN |
|
HCl |
1,0 |
|
H2SO4 |
1,2 |
|
H 2 C 2 O 4 |
1,3 |
|
NaHSO4 |
1,4 |
|
H 3 RO 4 |
1,5 |
|
Gastric juice |
1,6 |
|
Wine acid |
2,0 |
|
Lemon acid |
2,1 |
|
HNO 2 |
2,2 |
|
Lemon juice |
2,3 |
|
Lactic acid |
2,4 |
|
Salicylic acid |
2,4 |
|
table vinegar |
3,0 |
|
grapefruit juice |
3,2 |
|
CO 2 |
3,7 |
|
Apple juice |
3,8 |
|
H 2 S |
4,1 |
|
Urine |
4,8-7,5 |
|
Black coffee |
5,0 |
|
Saliva |
7,4-8 |
|
Milk |
6,7 |
|
Blood |
7,35-7,45 |
|
Bile |
7,8-8,6 |
|
ocean water |
7,9-8,4 |
|
Fe(OH)2 |
9,5 |
|
MgO |
10,0 |
|
Mg(OH)2 |
10,5 |
|
Na2CO3 |
|
|
Ca(OH)2 |
11,5 |
|
NaOH |
13,0 |
Fish eggs and fry are especially sensitive to changes in the pH of the medium. The table allows a number of interesting observations to be made. pH values, for example, immediately show the comparative strength of acids and bases. A strong change in the neutral medium is also clearly visible as a result of the hydrolysis of salts formed by weak acids and bases, as well as during the dissociation of acid salts.
Urine pH is not a good indicator of overall body pH, and it is not a good indicator of overall health.
In other words, no matter what you eat and at any urine pH, you can be absolutely sure that your arterial blood pH will always be around 7.4.
When a person consumes, for example, acidic foods or animal protein, under the influence of buffer systems, the pH shifts to the acid side (becomes less than 7), and when, for example, mineral water or plant foods are consumed, it shifts to alkaline (becomes more than 7). Buffer systems keep the pH in the acceptable range for the body.
By the way, doctors say that we tolerate the shift to the acid side (the same acidosis) much easier than the shift to the alkaline side (alkalosis).
It is impossible to shift the pH of the blood by any external influence.
THE MAIN MECHANISMS OF BLOOD PH MAINTENANCE ARE:
1. Buffer systems of blood (carbonate, phosphate, protein, hemoglobin)
This mechanism operates very quickly (fractions of a second) and therefore belongs to the rapid mechanisms for regulating the stability of the internal environment.
Bicarbonate blood buffer quite powerful and most mobile.
One of the important buffers of blood and other body fluids is the bicarbonate buffer system (HCO3/CO2): CO2 + H2O ⇄ HCO3- + H+ The main function of the blood bicarbonate buffer system is the neutralization of H+ ions. This buffer system plays a particularly important role because the concentrations of both buffer components can be adjusted independently of each other; [CO2] - by breathing, - in the liver and kidneys. Thus, it is an open buffer system.
The hemoglobin buffer system is the most powerful.
It accounts for more than half of the buffer capacity of the blood. The buffer properties of hemoglobin are due to the ratio of reduced hemoglobin (HHb) and its potassium salt (KHb).
Plasma proteins due to the ability of amino acids to ionization, they also perform a buffer function (about 7% of the buffer capacity of blood). In an acidic environment, they behave like acid-binding bases.
Phosphate buffer system(about 5% of the buffer capacity of the blood) is formed by inorganic blood phosphates. Acid properties are shown by monobasic phosphate (NaH 2 P0 4), and bases - by dibasic phosphate (Na 2 HP0 4). They function on the same principle as bicarbonates. However, due to the low content of phosphates in the blood, the capacity of this system is small.
2. Respiratory (pulmonary) system of regulation.
Due to the ease with which the lungs regulate CO2 concentration, this system has a significant buffering capacity. Removal of excess amounts of CO 2 , regeneration of bicarbonate and hemoglobin buffer systems are carried out easily.
At rest, a person emits 230 ml of carbon dioxide per minute, or about 15,000 mmol per day. When carbon dioxide is removed from the blood, an approximately equivalent amount of hydrogen ions disappears. Therefore, breathing plays an important role in maintaining the acid-base balance. So, if the acidity of the blood increases, then an increase in the content of hydrogen ions leads to an increase in pulmonary ventilation (hyperventilation), while carbon dioxide molecules are excreted in large quantities and the pH returns to normal levels.
An increase in the content of bases is accompanied by hypoventilation, resulting in an increase in the concentration of carbon dioxide in the blood and, accordingly, the concentration of hydrogen ions, and the shift in the reaction of the blood to the alkaline side is partially or completely compensated.
Consequently, the external respiration system is quite quickly (within a few minutes) able to eliminate or reduce pH shifts and prevent the development of acidosis or alkalosis: an increase in lung ventilation by 2 times increases blood pH by about 0.2; reducing ventilation by 25% can reduce the pH by 0.3-0.4.
3. Renal (excretory system)
Acts very slowly (10-12 hours). But this mechanism is the most powerful and is able to completely restore the pH of the body by removing urine with alkaline or acidic pH values. The participation of the kidneys in maintaining acid-base balance consists in removing hydrogen ions from the body, reabsorbing bicarbonate from the tubular fluid, synthesizing bicarbonate in case of its deficiency and removal in excess.
The main mechanisms for reducing or eliminating shifts in blood acid-base balance realized by kidney nephrons include acidogenesis, ammoniogenesis, phosphate secretion, and K+,Ka+-exchange mechanism.
The mechanism of blood pH regulation in the whole organism consists in the joint action of external respiration, blood circulation, excretion and buffer systems. So, if as a result of the increased formation of H 2 CO 3 or other acids, excess anions appear, they are first neutralized by buffer systems. In parallel, breathing and blood circulation are intensified, which leads to an increase in the release of carbon dioxide by the lungs. Non-volatile acids, in turn, are excreted in the urine or sweat.
Normally, blood pH can change only for a short time. Naturally, with damage to the lungs or kidneys, the body's functional capabilities to maintain pH at the proper level are reduced. If a large amount of acidic or basic ions appears in the blood, only buffer mechanisms (without the help of excretion systems) will not keep the pH at a constant level. This leads to acidosis or alkalosis. published
© Olga Butakova "Acid-base balance is the basis of life"
As we all remember from the school chemistry course, pH is a unit of hydrogen ion activity, equal to the reciprocal logarithm of the activity of hydrogen ions. Thus, water with a pH value of 7 has 10 -7 mol per liter of hydrogen ions, and water with a pH of 6 has 10 -6 mol per liter. The pH scale can range from 0 to 14.
In general, water with a pH less than 7 is considered acidic, while water with a pH greater than 7 is considered alkaline. The normal pH range for surface water systems is between 6.5 and 8.5 and for underground systems between 6 and 8.5.
The pH value of water (H 2 0) is 7 at 25 °C, but upon contact with carbon dioxide in the atmosphere, this equilibrium shifts to a pH of approximately 5.2. Due to the close relationship of pH to atmospheric gases and temperature, it is highly recommended that water be tested as soon as possible. After all, the pH of water is not a measure of the stability of an acidic or alkaline reaction and does not give a complete picture of the characteristics or reason for limiting water supply.
soft water
In general, water with a low pH (less than 6.5) is acidic, soft and corrosive. Thus, metal ions such as iron, manganese, copper, lead and zinc from the aquifer, plumbing and pipelines can penetrate into the water. Therefore, low pH water can:
- contain elevated levels of toxic metals;
- lead to premature damage to metal pipes;
- have a metallic or sour taste;
- dye linen;
- have a characteristic "blue-green" coloration of the sink and drains.
The main way to solve the problem of low pH water is to use a neutralizer. It feeds the solution into the water to prevent water from reacting with domestic plumbing or electrolytic corrosion. Typical Neutralizer - Chemical Neutralization with this agent increases the sodium content of the water.
hard water
Water with a pH above 8.5 is hard. It does not pose a health hazard, but may cause aesthetic problems. These problems include:
- Formation of "scale" or sediment on pipelines and fixtures.
- An alkaline taste in water that can make coffee taste bitter.
- Scale formation on dishes, washing machine, pools.
- Difficulty in obtaining foam from soaps and detergents and the formation of insoluble deposits on clothes, etc.
- Reducing the efficiency of electric water heaters.
Typically, these problems occur when the hardness ranges from 100 to 200 milligrams CaCO 3 /l, which is equivalent to 12 grams per gallon. Water can be softened through the use of ion exchange or the addition of ash, lime and soda, but both processes increase the sodium content of the water.
pH of drinking water
Careful attention to pH control is essential at all stages of water treatment to ensure satisfactory water quality and disinfection. Although water pH does not usually have a direct impact on consumers, it is one of the most important performance parameters for water quality. For effective disinfection with chlorine, the pH should preferably be less than 8. The pH of the water entering the distribution system must be controlled to minimize pipe corrosion. Failure to do so may result in contamination of drinking water and adverse effects on taste, odor and appearance.
The optimum pH value will vary for different materials depending on the composition of the water and the nature of the building materials used in the distribution system, but is most commonly in the range of 6.5-9.5. Extreme pH values can be the result of accidental spills, breakdowns in wastewater treatment plants.
The ideal pH level of ionized water for long-term human consumption is between 8.5 and 9.5 (and never exceeds 10.0) with an ideal ORP of around 200mV-300mV (and never above 400mV).
PH of pool water
As mentioned above, pH is an important characteristic not only for drinking water, but also for swimming pools, since chlorination is still mainly used to disinfect water, and when using chlorine, the effectiveness of disinfection is highly dependent on the initial pH value of the water.
Chlorine is the main disinfecting agent for preventing infections in public pools, but chlorine also reacts with organic matter in the water and forms disinfection by-products (HBPs): organic matter is a derivative of humic substances formed as a result of the interaction of water with sweat, urine, hair, skin cells and personal care product residue from swimmers. The content of PPD can be measured as the sum of all halogenated compounds. Some DAAs increase the risk of developing asthma, are carcinogenic, or irritate the eyes and skin.
Chlorine is a common name that forms chlorine gas that reacts with water. Dissolving in water, the acid forms hypochlorite and has a pKa value of 7.5.
Chloric acid is much more effective than hypochlorite at killing bacteria, cysts, spores, and inactive viruses. Thus, if the pH value of the swimming pool is at the lower end of the regulated range, less chlorine needs to be produced for the same degree of disinfection, and therefore less potentially dangerous RCPs are formed in the water. As shown by numerous studies, the optimal pH level of water in the pool lies in the range from 7.5 to 8.0. With a decrease in pH by only 1-0.5 units (up to 7.0-6.5), the level of PPD significantly increases, which, moreover, are also genotoxic.
Methods for determining pH
The pH scale is a logarithmic scale, which means that every 1 unit increase or decrease represents a change by a factor of 10. For example, a pH 11 solution is 10 times more alkaline than a pH 10 solution. There are several methods to determine the pH of water. .
pH Determination with Test Strips
Test strips are litmus paper that reacts by changing color to pH fluctuations. You can buy them at pet stores, as they are often used to determine the pH of water in aquariums (even a slight fluctuation in this indicator can lead to the death of fish).
On contact with the test strip will change. You only have to compare the final color with the sample color chart on the package and get a specific value. This method for determining pH is fast, simple, cheap, but has a fairly large error.
Litmus paper "Rottinger"
Purchase at medical equipment stores in your city. After analyzing various ph tests (from cheap Chinese to expensive Dutch), we came to the conclusion that the German Rottinger ph strips give the minimum error in the reading. The package comes with an indicator scale from 1 to 14 (the maximum available interval!) And 80 ph strips, which are enough for a long time. Using these strips, you can measure not only the ph of water, but also the ph of biological fluids such as saliva, urine, etc. Since good ph meters are quite expensive (about 3000 rubles), and you have to buy buffer solutions for calibration, then Rottinger litmus paper, the price of which does not exceed 250-350 rubles, will serve you as an indispensable assistant in accurately determining the ph level.
pH determination with a pH meter
A water sample (20-30 ml) is taken into a plastic or glass cup. The sensor of the device is rinsed with a small amount of distilled water, and then immersed in the solution together with the temperature sensor. The instrument's scale shows you the exact pH value of the test solution. In this case, it should be taken into account that the accuracy of measurements is affected by regular calibration of the instrument, for which standard solutions with a known pH value are used. This method for determining pH is accurate, simple, fast, but requires more material costs compared to the previous one and the simplest skills in working with laboratory equipment and chemical solutions.
Thus, the pH of water is not just a term from a school chemistry course, but also an indicator of water quality that must be monitored in order to avoid problems with equipment and health.
Hydrogen indicator (pH factor) is a measure of the activity of hydrogen ions in a solution, quantifying its acidity. When the pH is not at the optimum level, the plants begin to lose the ability to absorb some of the elements needed for healthy growth. For all plants there is a specific pH level that allows you to achieve maximum results when growing. Most plants prefer a slightly acidic growing medium (between 5.5-6.5).
Hydrogen indicator in formulas
In very dilute solutions, the pH is equivalent to the concentration of hydrogen ions. Equal in modulus and opposite in sign to the decimal logarithm of the activity of hydrogen ions, expressed in moles per liter:
pH = -lg
Under standard conditions, the pH value lies in the range from 0 to 14. In pure water, at neutral pH, the concentration of H + is equal to the concentration of OH - and is 1·10 -7 mol per liter. The maximum possible pH value is defined as the sum of pH and pOH and is equal to 14.
Contrary to popular belief, pH can vary not only in the range from 0 to 14, but can also go beyond these limits. For example, at a concentration of hydrogen ions = 10 −15 mol/l, pH = 15, at a concentration of hydroxide ions of 10 mol/l pOH = −1.
It's important to understand! The pH scale is logarithmic, which means that each unit of change equals a tenfold change in the concentration of hydrogen ions. In other words, a pH 6 solution is ten times more acidic than a pH 7 solution, and a pH 5 solution will be ten times more acidic than a pH 6 solution and a hundred times more acidic than a pH 7 solution. This is means that when you are adjusting the pH of your nutrient solution and you need to change the pH by two points (e.g. from 7.5 to 5.5) you must use ten times more pH adjuster than if you only changed the pH by one point (from 7.5 to 6.5). ).
Methods for determining the pH value
Several methods are widely used to determine the pH value of solutions. The pH value can be approximated with indicators, accurately measured with a pH meter, or determined analytically by performing an acid-base titration.
Acid-base indicators
For a rough estimate of the concentration of hydrogen ions, acid-base indicators are widely used - organic dye substances, the color of which depends on the pH of the medium. The most famous indicators include litmus, phenolphthalein, methyl orange (methyl orange) and others. Indicators can exist in two differently colored forms, either acidic or basic. The color change of each indicator occurs in its acidity range, usually 1-2 units.
Universal indicator
To extend the working range of pH measurement, the so-called universal indicator is used, which is a mixture of several indicators. The universal indicator consistently changes color from red through yellow, green, blue to purple when moving from an acidic region to a basic one.
Solutions of such mixtures - "universal indicators" are usually impregnated with strips of "indicator paper", with which you can quickly (with an accuracy of pH units, or even tenths of pH) determine the acidity of the aqueous solutions under study. For a more accurate determination, the color of the indicator paper obtained by applying a drop of solution is immediately compared with the reference color scale, the form of which is shown in the images.
Determination of pH by the indicator method is difficult for cloudy or colored solutions.
Given the fact that the optimal pH values for nutrient solutions in hydroponics have a very narrow range (usually from 5.5 to 6.5), other combinations of indicators are also used. So, for example, ours has a working range and a scale from 4.0 to 8.0, which makes such a test more accurate than universal indicator paper.
pH meter
The use of a special device - a pH meter - allows you to measure pH in a wider range and more accurately (up to 0.01 pH units) than with universal indicators. The method is convenient and highly accurate, especially after calibration of the indicator electrode in the selected pH range. Allows you to measure the pH of opaque and colored solutions and is therefore widely used.
Analytical volumetric method
Analytical volumetric method - acid-base titration - also gives accurate results for determining the acidity of solutions. A solution of known concentration (titrant) is added dropwise to the test solution. When they are mixed, a chemical reaction takes place. The equivalence point - the moment when the titrant is exactly enough to completely complete the reaction - is fixed using an indicator. Further, knowing the concentration and volume of the added titrant solution, the acidity of the solution is calculated.
Effect of Temperature on pH Values
The pH value can change over a wide range as the temperature changes. Thus, a 0.001 molar solution of NaOH at 20°C has pH=11.73, and at 30°C pH=10.83. The effect of temperature on pH values is explained by the different dissociation of hydrogen ions (H+) and is not an experimental error. The temperature effect cannot be compensated by the electronics of the pH meter.
Adjusting the pH of the Nutrient Solution
Acidification of the nutrient solution
The nutrient solution usually needs to be acidified. The absorption of ions by plants causes a gradual alkalinization of the solution. Any solution having a pH of 7 or higher will most often need to be adjusted to the optimum pH. Various acids can be used to acidify the nutrient solution. Most often, sulfuric or phosphoric acid is used. A better solution for hydroponic solutions are buffer additives such as and. These products not only bring the pH values to the optimum, but also stabilize the values for a long period.
When adjusting the pH with both acids and alkalis, rubber gloves should be worn to avoid burns to the skin. An experienced chemist skillfully handles concentrated sulfuric acid, he adds acid to water drop by drop. But as a beginner hydroponist, it's probably best to ask an experienced chemist to prepare a 25% sulfuric acid solution. While the acid is being added, the solution is stirred and its pH is determined. Having learned the approximate amount of sulfuric acid, in the future it can be added from a graduated cylinder.
Sulfuric acid must be added in small portions so as not to acidify the solution too much, which then has to be alkalized again. For an inexperienced worker, acidification and alkalization can go on indefinitely. In addition to wasting time and reagents, such regulation unbalances the nutrient solution due to the accumulation of ions that the plants do not need.
Alkalinization of the nutrient solution
Too acidic solutions are alkalized with sodium hydroxide (sodium hydroxide). As its name suggests, it is caustic so rubber gloves should be worn. It is recommended to purchase caustic sodium in the form of pills. In household chemical stores, caustic sodium can be purchased as a pipe cleaner, such as Mole. Dissolve one pill in 0.5 liters of water and gradually pour the alkaline solution into the nutrient solution with constant stirring, checking its pH frequently. No mathematical calculations can calculate how much acid or alkali needs to be added in this or that case.
If you want to grow several crops in one pallet, you need to select them so that not only their optimal pH, but also the needs for other growth factors coincide. For example, yellow daffodils and chrysanthemums need a pH of 6.8 but a different humidity regime so they cannot be grown on the same pallet. If you give daffodils as much moisture as chrysanthemums, the daffodil bulbs will rot. In experiments, rhubarb reached its maximum development at pH 6.5, but could grow even at pH 3.5. Oats, which prefer a pH around 6, produce good yields even at pH 4 if the amount of nitrogen in the nutrient solution is greatly increased. Potatoes grow over a fairly wide pH range, but grow best at a pH of 5.5. Below this pH, high yields of tubers are also obtained, but they acquire a sour taste. To obtain maximum yields of high quality, the pH of nutrient solutions must be precisely controlled.
pH value and its influence on the quality of drinking water.
What is pH?
pH("potentia hydrogeni" - the strength of hydrogen, or "pondus hydrogenii" - the weight of hydrogen) is a unit of measurement of the activity of hydrogen ions in any substance, quantitatively expressing its acidity.
This term appeared at the beginning of the twentieth century in Denmark. The pH index was introduced by the Danish chemist Soren Petr Lauritz Sorensen (1868-1939), although his predecessors also have statements about a certain “power of water”.
Hydrogen activity is defined as the negative decimal logarithm of the concentration of hydrogen ions, expressed in moles per liter:
pH = -log
For simplicity and convenience, pH was introduced in the calculations. pH is determined by the quantitative ratio of H+ and OH- ions in water, which are formed during the dissociation of water. It is customary to measure the pH level on a 14-digit scale.
If the water has a reduced content of free hydrogen ions (pH greater than 7) compared to hydroxide ions [OH-], then the water will have alkaline reaction, and with an increased content of H + ions (pH less than 7) - acid reaction. In perfectly pure distilled water, these ions will balance each other.
acid environment: >
neutral environment: =
alkaline environment: >
When the concentrations of both types of ions in a solution are the same, the solution is said to be neutral. In neutral water, the pH is 7.
When various chemicals are dissolved in water, this balance changes, which leads to a change in the pH value. When acid is added to water, the concentration of hydrogen ions increases, and the concentration of hydroxide ions decreases accordingly, when alkali is added, on the contrary, the content of hydroxide ions increases, and the concentration of hydrogen ions decreases.
The pH indicator reflects the degree of acidity or alkalinity of the environment, while "acidity" and "alkalinity" characterize the quantitative content in water of substances that can neutralize alkalis and acids, respectively. As an analogy, we can give an example with temperature, which characterizes the degree of heating of a substance, but not the amount of heat. By dipping our hand into the water, we can tell whether the water is cool or warm, but at the same time we will not be able to determine how much heat is in it (i.e., relatively speaking, how long this water will cool down).
pH is considered one of the most important indicators of drinking water quality. It shows the acid-base balance and influences how chemical and biological processes will proceed. Depending on the pH value, the rate of chemical reactions, the degree of corrosiveness of water, the toxicity of pollutants, etc. can change. Our well-being, mood and health directly depend on the acid-base balance of the environment of our body.
Modern man lives in a polluted environment. Many people buy and consume food made from semi-finished products. In addition, almost every person is exposed to stress on a daily basis. All this affects the acid-base balance of the body's environment, shifting it towards acids. Tea, coffee, beer, carbonated drinks lower the pH in the body.
It is believed that an acidic environment is one of the main causes of cell destruction and tissue damage, the development of diseases and the aging process, and the growth of pathogens. In an acidic environment, building material does not reach the cells, the membrane is destroyed.
Outwardly, the state of the acid-base balance of a person's blood can be judged by the color of his conjunctiva in the corners of his eyes. With an optimal acid-base balance, the color of the conjunctiva is bright pink, but if a person has an increased alkalinity of the blood, the conjunctiva acquires a dark pink color, and with an increase in acidity, the color of the conjunctiva becomes pale pink. Moreover, the color of the conjunctiva changes already 80 seconds after the use of substances that affect the acid-base balance.
The body regulates the pH of internal fluids, maintaining the values at a certain level. The acid-base balance of the body is a certain ratio of acids and alkalis that contributes to its normal functioning. Acid-base balance depends on maintaining relatively constant proportions between intercellular and intracellular waters in the tissues of the body. If the acid-base balance of fluids in the body is not constantly maintained, normal functioning and the preservation of life will be impossible. Therefore, it is important to control what you consume.
Acid-base balance is our indicator of health. The more acidic we are, the sooner we age and the more we get sick. For the normal functioning of all internal organs, the pH level in the body must be alkaline, in the range from 7 to 9.
The pH inside our body is not always the same - some parts are more alkaline and some are more acidic. The body regulates and maintains pH homeostasis only in certain cases, such as blood pH. The pH level of the kidneys and other organs, the acid-base balance of which is not regulated by the body, is affected by the food and drinks that we consume.
blood pH
The blood pH level is maintained by the body in the range of 7.35-7.45. The normal pH of human blood is 7.4-7.45. Even a slight deviation in this indicator affects the ability of the blood to carry oxygen. If the pH of the blood rises to 7.5, it carries 75% more oxygen. With a decrease in blood pH to 7.3, it is already difficult for a person to get out of bed. At 7.29, he can fall into a coma, if the blood pH drops below 7.1, the person dies.
Blood pH must be maintained in a healthy range, so the body uses organs and tissues to keep it constant. As a consequence, the pH level of the blood does not change due to the consumption of alkaline or acidic water, but the tissues and organs of the body used to adjust the pH of the blood change their pH.
kidney pH
The pH parameter of the kidneys is influenced by water, food, and metabolic processes in the body. Acidic foods (such as meats, dairy, etc.) and drinks (sweetened sodas, alcoholic beverages, coffee, etc.) lead to low pH levels in the kidneys because the body excretes excess acidity through urine. The lower the pH of the urine, the harder it is for the kidneys to work. Therefore, the acid load on the kidneys from such foods and drinks is called the potential acid-renal load.
The use of alkaline water benefits the kidneys - there is an increase in the pH level of the urine, the acid load on the body is reduced. Increasing the pH of the urine raises the pH of the body as a whole and rids the kidneys of acidic toxins.
stomach pH
An empty stomach contains no more than a teaspoon of stomach acid produced in the last meal. The stomach produces acid as needed when eating food. The stomach does not release acid when a person drinks water.
It is very helpful to drink water on an empty stomach. The pH increases at the same time to the level of 5-6. An increased pH will have a mild antacid effect and lead to an increase in beneficial probiotics (beneficial bacteria). Increasing the pH of the stomach raises the pH of the body, which leads to healthy digestion and relief from the symptoms of indigestion.
subcutaneous fat pH
The fatty tissues of the body have an acidic pH because excess acids are deposited in them. The body has to store acid in fatty tissues when it cannot be removed or neutralized in other ways. Therefore, the shift in the pH of the body to the acid side is one of the factors of excess weight.
The positive effect of alkaline water on body weight is that alkaline water helps to remove excess acid from the tissues, as it helps the kidneys to work more efficiently. This helps to control weight, since the amount of acid that the body must "store" is greatly reduced. Alkaline water also enhances the results of a healthy diet and exercise by helping the body deal with the excess acid produced by fatty tissue during weight loss.
Bones
Bones have an alkaline pH as they are mostly made up of calcium. Their pH is constant, but if the blood needs pH adjustment, calcium is taken from the bones.
The benefit that alkaline water brings to the bones is to protect them by reducing the amount of acid that the body has to deal with. Studies have shown that drinking alkaline water reduces bone resorption - osteoporosis.
liver pH
The liver has a slightly alkaline pH, which is affected by both food and drink. Sugar and alcohol must be broken down in the liver, and this leads to excess acid.
The benefits of alkaline water for the liver are the presence of antioxidants in such water; it has been found that alkaline water enhances the work of two antioxidants located in the liver, which contribute to more effective blood purification.
body pH and alkaline water
Alkaline water allows the parts of the body that maintain the pH of the blood to work more efficiently. Increasing the pH level in the parts of the body responsible for maintaining blood pH will help these organs stay healthy and function efficiently.
Between meals, you can help your body balance its pH by drinking alkaline water. Even a small increase in pH can have a huge impact on health.
According to research by Japanese scientists, the pH of drinking water, which is in the range of 7-8, increases the life expectancy of the population by 20-30%.
Depending on the pH level, water can be divided into several groups:
strongly acidic waters< 3
acidic waters 3 - 5
slightly acidic waters 5 - 6.5
neutral waters 6.5 - 7.5
slightly alkaline waters 7.5 - 8.5
alkaline waters 8.5 - 9.5
highly alkaline waters > 9.5
Typically, the pH level of drinking tap water is within the range at which it does not directly affect the consumer quality of water. In river waters pH is usually within 6.5-8.5, in atmospheric precipitation 4.6-6.1, in swamps 5.5-6.0, in sea waters 7.9-8.3.
WHO does not offer any medically recommended value for pH. It is known that at low pH, water is highly corrosive, and at high levels (pH>11), water acquires a characteristic soapiness, an unpleasant odor, and can cause eye and skin irritation. That is why for drinking and domestic water, the pH level in the range from 6 to 9 is considered optimal.
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Interesting to know: The German biochemist OTTO WARBURG, who was awarded the Nobel Prize in Physiology or Medicine in 1931, proved that the lack of oxygen (an acidic pH<7.0) в тканях приводит к изменению нормальных клеток в злокачественные.
The scientist found that cancer cells lose their ability to develop in an environment saturated with free oxygen with a pH value of 7.5 and higher! This means that when the fluids in the body become acidic, the development of cancer is stimulated.
His followers in the 60s of the last century proved that any pathogenic flora loses its ability to multiply at pH = 7.5 and above, and our immune system can easily cope with any aggressors!
To preserve and maintain health, we need proper alkaline water (pH=7.5 and above). This will allow you to better maintain the acid-base balance of body fluids, since the main living environments have a slightly alkaline reaction.
Already in a neutral biological environment, the body can have an amazing ability to heal itself.
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Hydrogen index, pH (pronounced “peash”, English pronunciation of English pH - piː "eɪtʃ," pee ") - a measure of activity (in very dilute solutions it is equivalent to concentration) of hydrogen ions in a solution, and quantitatively expressing its acidity, is calculated as the negative (reverse sign) logarithm of the tenth logarithm of the activity of hydrogen ions, expressed in moles per liter: Story This concept was introduced in 1909 by the Danish chemist Sorensen. The indicator is called pH, after the first letters of the Latin words potentia hydrogeni - the strength of hydrogen, or pondus hydrogeni - the weight of hydrogen. In general, in chemistry, the combination pX is used to denote a value equal to −lg X, and the letter H in this case denotes the concentration of hydrogen ions (H +), or, more precisely, the thermodynamic activity of hydronium ions. Equations relating pH and pOH pH value output In pure water at 25 ° C, the concentrations of hydrogen ions () and hydroxide ions () are the same and amount to 10 −7 mol / l, this directly follows from the definition of the ion product of water, which is equal to and is 10 −14 mol² / l² (at 25°C). When the concentrations of both types of ions in a solution are the same, the solution is said to be neutral. When an acid is added to water, the concentration of hydrogen ions increases, and the concentration of hydroxide ions decreases accordingly, when a base is added, on the contrary, the content of hydroxide ions increases, and the concentration of hydrogen ions decreases. When > they say that the solution is acidic, and when > - alkaline. For convenience of presentation, in order to get rid of the negative exponent, instead of the concentrations of hydrogen ions, they use their decimal logarithm, taken with the opposite sign, which is actually the hydrogen indicator - pH. pOH The reciprocal pH value has become somewhat less widespread - an indicator of the basicity of the solution, pOH, equal to the negative decimal logarithm of the concentration in the solution of OH - ions: as in any aqueous solution at 25 °C, it is obvious that at this temperature: pH values in solutions of different acidity
- Contrary to popular belief, pH can vary not only in the range from 0 to 14, but can also go beyond these limits. For example, at a concentration of hydrogen ions = 10 −15 mol / l, pH = 15, at a concentration of hydroxide ions of 10 mol / l pOH = −1.
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- For a rough estimate of the concentration of hydrogen ions, acid-base indicators are widely used - organic dye substances, the color of which depends on the pH of the medium. The most famous indicators include litmus, phenolphthalein, methyl orange (methyl orange) and others. Indicators can exist in two differently colored forms, either acidic or basic. The color change of each indicator occurs in its acidity range, usually 1–2 units.
- To extend the working range of pH measurement, the so-called universal indicator is used, which is a mixture of several indicators. The universal indicator consistently changes color from red through yellow, green, blue to purple when moving from an acidic to an alkaline region. Determination of pH by the indicator method is difficult for cloudy or colored solutions.
- The use of a special device - a pH meter - allows you to measure pH in a wider range and more accurately (up to 0.01 pH units) than with indicators. The ionometric method for determining pH is based on measuring the EMF of a galvanic circuit with a millivoltmeter-ionometer, including a special glass electrode, the potential of which depends on the concentration of H + ions in the surrounding solution. The method is convenient and highly accurate, especially after calibrating the indicator electrode in a selected pH range, it allows measuring the pH of opaque and colored solutions and is therefore widely used.
- Analytical volumetric method - acid-base titration - also gives accurate results for determining the acidity of solutions. A solution of known concentration (titrant) is added dropwise to the test solution. When they are mixed, a chemical reaction takes place. The equivalence point - the moment when the titrant is exactly enough to completely complete the reaction - is fixed using an indicator. Further, knowing the concentration and volume of the added titrant solution, the acidity of the solution is calculated.
- Effect of Temperature on pH Values