What is the pH of water? How to apply? Cold Or Heat Flow Meter,Ultrasonic Cold Or Heat Flowmeter Machine,Dc Pipeline Integrated Heat Flowmeter,Electromagnetic Cold Flowmeter Jiangsu Baichuang Instrument Group Co.,Ltd , https://www.subcip.com
The pH of water refers to the negative logarithm of the H+ concentration in water. which is:
pH=一lg[H+]
Since the H+ concentration of water is small, it is inconvenient in application, and it is convenient to use pH to reflect the pH of the aqueous solution. The application is shown in Table 1-24.
When pH = 7, water [H+] = [OH-], at which time the aqueous solution is neutral.
An alkaline solution when pH > 7; an acidic solution when pH < 7.
What factors affect the pH of natural water?
Since most of the water contains carbonates and bicarbonates, the pH of natural water is generally between 7 and 8. When the water contains a large amount of free carbon dioxide, or is contaminated by acidic industrial wastewater, the pH of the water will decrease; in some mountains, forests or swamps, the water will have a large pH due to the large amount of humic acid. Will be lower.
Acidic water has a corrosive effect on concrete, metal pipes and the like. When the water contains alkaline substances (such as carbonates or hydroxides), the pH of the water increases. Alkaline water may cause the precipitation of certain dissolved salts, changing the original characteristics of the water.
The pH of water between 6.5 and 9.5 does not affect the normal drinking of humans, nor does it have adverse effects on equipment and piping.
How is natural water classified?
There are several methods commonly used to classify natural water according to its chemical composition:
(1) According to the ion content in water, 1 according to the salt content, low salt content water - salt content below 200mg / L;
Medium salt water - salt content between 200 ~ 500mg / L;
Higher salt content water - salt content between 500 ~ 1000mg / L;
High salt content water - salt content above 1000mg / L.
2 according to the hardness of the soft water - hardness is 1.0mmoL / I. the following;
Soft water - hardness is 1. O ~ 3.0 mmol / I. between;
Medium hard water - hardness is 3. O ~ 6.0mmol / 1. between;
Hard water - hardness is 3. O ~ 9.0mmoL / L.
(2) According to the content of anion and cation, this classification method is currently used for groundwater. It is based on the amount of ionic substances in groundwater. There are only six ions that reach this order of magnitude, namely: Na+, Mg2+, ca2+, cl-, SO-, and HCOf. Since one cation and one anion are not separately present in water, only three cations and three anions can be combined with one another as shown in Tables 1-25.
In the naming, which kind of ion can be used, what kind of name is given. For example, the anion content may be referred to as chloride water, sulfuric acid brine, bicarbonate brine, sulfate bicarbonate brine, or the like. Further, the cation may be referred to as sodium water, magnesium water, sodium magnesium water, sodium calcium water or the like.
(3) Classification according to the main components and ions. This classification is based on the most abundant anions as the classification basis, and the most anions are divided into three major categories: bicarbonate and carbonated water, sulfuric acid water and chlorinated water. In each of the major categories, the main cations were divided into three groups: calcium group, magnesium group and sodium group, and each group of water was divided into four different types according to the relative content of cations and anions. This gives 27 kinds of water. See Table 1-26.
When naming, according to the water quality analysis results, a certain water can be called a certain type, a certain group, a certain type of water. The class is represented by the first letter of the corresponding anion name (C, S, c1), the group is represented by the symbol of the chemical composition, and the type is represented by the Roman numeral. For example, [C]Ca I represents carbonate, calcium group, and type I water, which means that HCOf is the most in the anion, Ca2+ is the most in the cation, and the amount of HCOf is greater than that of water.
Water pH and application