Mole is the unit to express the quantity of matter, and each mole of matter contains Avon Gadereau constant particles.
According to the accurate determination of scientific experiments, it is known that the number of carbon atoms in 12g carbon with a relative atomic mass of12 is about 6.02× 10 23.
Scientifically, the collective containing 23 particles of 6.02×10 is regarded as a unit, which is called a mole. It is a unit (symbol n) that represents the quantity of a substance, which is referred to as Mo for short, and the unit symbol is mol.
The carbon atom of 1mol contains 6.02× 10 23 carbon atoms, and its mass is 12g.
The sulfur atom of 1mol contains 6.02× 10 23 sulfur atoms, and its mass is 32g.
Similarly, the mass of any substance in 1 mol is in grams, which is numerically equal to the relative atomic mass (molecular weight) of atoms.
The molecular formula of water is 18, the mass of 1mol is 18g, and it contains 6.02× 10 23 water molecules.
Generally, the mass of the substance 1mol is called the molar mass of the substance (symbol m), and the unit of molar mass is gram/mol, which is read as "gram per mole" (symbol G/mol). For example, the molar mass of water is 18g/mol, written as m (H2O) = 18g/.
What is the relationship between mass (m), quantity (n) and [1] molar mass (m)? Existing: n=m/M
Chemical equations can express the ratio of quantity and mass of substances between reactants and products. For example:
The ratio of coefficients is 2∶ 1∶2.
The ratio of particle number is 2∶ 1∶2.
The ratio of substances is 2∶ 1∶2.
The mass ratio is 4∶32∶36.
From the above analysis, it can be seen that the ratio of the coefficients of each substance in the chemical equation is the ratio of the amount of substances between them. Using this principle, we can calculate the amount of each substance according to the chemical equation.
The unit of quantity of matter, with the symbol of mole, is one of the seven basic units of the international system of units. Mole is the amount of substance in a system, and the number of elementary particles in the system is equal to the number of atoms in 12g 12C. When using moles, you should specify basic particles, which can be atoms, molecules, ions and other particles, or a specific combination of these particles.
C (carbon) 12= 12, which is the international standard (formula) of relative atomic mass. It is known that 12g 12C contains 6.022 1367× 10 23 carbon atoms. This number is called Avon Gadereau number, so it can also be said that the amount of matter containing several Avon Gadereau elementary particles is 1mol. For example, 1 mole of oxygen molecule contains 23 oxygen molecules of 6.0221367×10. Its mass is 3 1.9988g 1mol. Hydrogen ions contain 6.022 1367× 10 23 hydrogen ions, and its mass is1.00794g.
Moore is the seventh basic unit of the International System of Units (SI), which was joined by 14 [2] International Metrology Conference and 4 1 countries in the month of 18+0. Mole is used to calculate the number of particles, the mass of matter, the volume of gas, the concentration of solution, the change of heat during the reaction and so on.
197 1 The 14th International Metrology Conference defined the mole in the following two paragraphs: "Mole is the amount of substances in a system, and the number of basic units contained in this system is equal to the number of atoms in 0.0 12kg carbon-12." "When using moles, you should specify the basic unit, which can be atoms, molecules, ions, electrons and other particles, or a specific combination of these particles." The last two paragraphs should be regarded as a whole. The number of carbon atoms in 0.0 12kg carbon-12 nuclide is Avon Garderot constant (NA). At present, the approximate value measured in the experiment is NA = 6.02× 10 23. Mole is different from ordinary units. It has two characteristics: ① The basic units for measuring micro, such as molecules and ions, cannot be used to measure macro-substances. (2) it takes Avon Gadereau number as the unit of measurement, and it is a batch, not a number, to measure the number of particles such as molecules and atoms. It can also be used to measure the specific combination of microscopic particles. For example, the amount of sulfuric acid is measured in moles, that is, 1mol sulfuric acid contains 6.02× 1023 sulfuric acid molecules. Molar is the most widely used unit of measurement in chemistry, such as calculation of chemical reaction equation, calculation in solution, preparation and dilution of solution, calculation of chemical equilibrium, molar volume of gas, thermochemistry and so on. [Edit this paragraph] At the beginning of the seventh century, the forces of Islam rose rapidly in the Arabian Peninsula and established a huge Islamic empire. Geographically, it inherited most of the territory of the ancient Persian kingdom, and its territory was vast enough to be proud of the Macedonian Empire and the powerful Roman Empire in Alexandria. The Islamic Empire, in fact, was a master of western culture at that time, and its achievements could only be matched by the Tang Empire, which was at the peak of East Asian civilization at the same time.
At this time, the European continent, after experiencing the splendid civilization of ancient Greece and Rome, suddenly fell into the dark Middle Ages, and the dull and cruel religious rule hindered the progress of western civilization.
In the 8th century AD, the North African Moors who believed in Islam invaded Spain from the Strait of Gibraltar and occupied the Iberian Peninsula (Pyrenees Peninsula). Since then, the Moorish dynasty has ruled Spain for more than 700 years.
The rule of this period is directly reflected in Cervantes' masterpiece Don Quixote. At that time, the most civilized city in Europe was Godova under Moorish rule. The brave Arab army has been heading for France, but the fierce offensive was blocked because it didn't adapt to the climate and terrain there.
However, the good times did not last long. The prosperity of Christian civilization also marks the decline of Islamic civilization. By the13rd century, the Moors had been able to settle in Spain. It was at this time that the Moors built a world-famous palace, Alhambra, on Mount Alhambra, the capital city of Grenada. This is the last stronghold for the Moors to resist the northern Christian countries.
The Nahid dynasty of the Moors was not enterprising, but indulged in pleasure and compromised for peace. However, the decline of the whole Islamic world is irreversible, and it has been destroyed by internal disputes, crusades and Mongolian soldiers, completely losing its former glory.
Although the Moors breathed in Grenada for more than a hundred years, they were eventually driven back to their desert hometown in Morocco, North Africa by Spanish Catholics. The rule of Islam in Europe officially ended. [Edit this paragraph] Raymond Cecil Moore (1892.2.20, Roslin, Washington, USA? 6? Lawrence, Kansas, 5 1974.4. 16)
It was also translated by Moore.
American paleontologist, famous for his research on Paleozoic sea lilies, bryozoa and corals. 19 13? 6? From 565438 to 0949, he was a member of the US Geological Survey. 19 19 Professor, University of Kansas. 1954 as the chief geologist of Kansas Geological Survey. He is the organizer and editor of the Paper on Paleontology of Invertebrates (1953), and the author of this work includes 150 experts working in this field all over the world. He is the author of Geohistory (1933), Introduction to Geohistory (1949) and Invertebrate Fossils (1952).
What are molar extinction coefficient, molar absorption coefficient and molar absorption coefficient?
Spectrophotometry is a method based on the selective absorption of electromagnetic radiation by substances with different molecular structures, which belongs to molecular absorption spectrum analysis. When light passes through the solution, the molecules of the measured substance absorb monochromatic light with a certain wavelength, and the intensity of the absorbed light is proportional to the distance through which the light passes. Although Bouguer had put forward the mathematical expression of the above relationship as early as 1729, it is generally believed that Lambert first discovered the expression in 1760, and its mathematical form is:
T=I/I0= 10(-kb)
Where I0 is the incident light intensity, I is the transmitted light intensity, 10(-kb) is the exponent based on 10, k is a constant, and b is the optical path length (usually expressed in cm).
Beer's law is equivalent to Bouguer's law, except that Beer's law is expressed by concentration. Combine these two laws to form Bill-Bouguer Law:
T=I/I0= 10(-kb)
Where c is the concentration of light-absorbing substance (usually in g/L or mg/L). After the logarithm of the above formula is based on 10, a linear expression is obtained:
a =-logT =-log(I/I0)= log(I0/I)=εBC
Where a is absorbance and ε is molar absorption coefficient or extinction coefficient.
The above expression is usually called Beer's Law. It shows that when monochromatic light with a specific wavelength passes through the solution, the absorbance of the sample is directly proportional to the concentration of absorbent in the solution and the distance through which the light passes.
When the wavelength, solution and temperature are determined, the molar extinction coefficient is determined by the characteristics of a given substance. In fact, the measured molar extinction coefficient is also related to the instrument used. Therefore, in quantitative analysis, the molar extinction coefficient of known substances is usually not used, but one or more substances with known concentrations are used to make calibration or working curves.
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① Absorption coefficient: The mathematical expression of Beer's Law is A=kbc. If the concentration c of the solution is in the unit of g/L and the optical path b is in the unit of cm, the constant k is called the absorption coefficient, expressed as a, and the unit is L/(g cm) [L/(g cm]. A = KBC can be written as A=abc. ② molar absorption coefficient: when the formula A=kbc is 1 mol/L and b is 1cm, the coefficient k is called molar absorption coefficient, expressed by ε, and the unit is l/(mol cm) [l/(mol cm)]. A=kbc can be written as a = ε C. In practical work, we can't directly measure the absorbance with a high concentration solution of 1mol/L, but measure the absorbance when diluted to an appropriate concentration for calculation. ε value is related to the wavelength of incident light and the properties of solution. For example, when NADH is at 260nm, ε is 15000, written as ε 260 NADH =15×103; ε is 6220 at 340nm, and ε340NADH=6.22× 103. ③ Specific absorption coefficient: If C is the percentage concentration (w/v) and B is cm in formula A=kbc, the constant k can be expressed by E%, which is called specific absorption coefficient or percentage absorption coefficient, and A=kbc can be written as A=E%bc. When the chemical structure of the measured object is known, the ε value can be analyzed. If the chemical structure of the measured object is unknown, ε cannot be determined. At this time, it is very convenient to analyze with a specific absorption coefficient. A, ε and E are often used for rough quantitative analysis, mainly for qualitative analysis. A large retail complex consisting of many shops and restaurants in a large shopping mall or large building. "
Mall can be said to be the top form of large-scale commercial real estate in the world, which was born with the suburbanization of family cars and houses. It is the product of modern industrial civilization and commercial articles, and belongs to a new type of compound commercial format.
Mall is often labeled with various commercial real estate concepts: dynamic Mall, lifestyle Mall, shopping center, pan-commercial Mall, shopping plaza, shopping park, theme shopping park, experience Mall, pan-commercial Mall and dynamic Mall.
Shopping malls are a way of life for the middle class. In addition to shopping, it also provides one-stop service for entertainment and leisure. The goods and services sold by Mall are not necessarily the most expensive, nor the latest fashion, which often symbolizes entering the mainstream society, but the mainstream has not lost its diversity. Teenagers think mall is cool and linger; Adults love shopping when they have nothing to do, making it a habit and hobby. [Editor's Note] Moore Moore, formerly known as Tsinghua Professional Manager Outward Bound Training Center, is one of the fastest-growing management consulting and training companies in China, headquartered in Beijing. Moore Changchun Outward Bound Training Base is located in Lianhuashan Ski Resort in Changchun. There are 25 high-altitude training programs and more than 40 low-altitude training programs, which can accommodate about 1 000 people for outward bound training at the same time. It is the only experiential training base in China with OB and PA dual systems.
Moore has successfully collected the experience of outward bound training at home and abroad, and formed a training institution that focuses on base training and combines various training forms, such as base expansion, field survival, orienteering and jungle field battle (real CS), ice and snow expansion, water training and military special training. Moore integrates outdoor, outdoor, ice and snow, outdoor, water and other expansion training activities, and can provide all-weather experiential training all year round, which has become Moore's uniqueness. Moore spared no effort to build a learning individual, learning organization and learning society. [Edit this paragraph] Online game (Moore Manor) Moore Manor (hereinafter referred to as Moore)
Suitable for people: children
Game language: Chinese
Development team: Taomi. com
Operating company: Taomi. com
Game abbreviation: Moore Manor
Operating state: normally open
Introduction information:
Moore Manor is a happy and wonderful online virtual paradise. Health, happiness, creation and sharing are the themes of this paradise. In Moore Manor, every little friend is transformed into a lovely little mole Moore, whose currency is bean-like Moore beans. Every little mole has to rely on his own labor to get mole beans, buy himself beautiful clothes with mole beans, bring his favorite play props, play games with other little moles, play with water and hide-and-seek, come to the snow-capped mountains together, have an exciting Moore skiing competition and go into the mysterious black forest to find out. A hearty tomato fight, a lovely ram, and a super ram with ancient magical power. All the happiness of the wonderful Moore Manor ... adults and children will find their own childhood memories in Moore Manor. ...