What Is a Concentration Unit?

Is a noun in analytical chemistry. The meaning is the concentration expressed in moles of solute contained in 1 liter of solution. The physical quantity of the solution composition is expressed by the amount (moles) of the solute substance contained in a unit volume, which is called the molar concentration of the solute, and is also called the amount concentration of the solute substance.

[nóng dù]

Is a noun in analytical chemistry. Meaning is contained in 1 liter of solution

Concentration refers to

The amount of solute contained in a unit solution is called the concentration of the solution

The more solute content, the greater the concentration

The symbol is C and the unit is mol / L. The formula is: C = n / V. C = 1000 / M

Concentration refers to

Blood concentration refers to the steady-state concentration of the drug in human blood. Steady-state concentration means that the daily blood drug concentration of the patient is relatively constant and stable in the effective range. Each drug takes a certain amount of time to reach steady state concentrations. Antiepileptic drug reaches steady state concentration

Solution concentration can be divided into

For atmospheric pollutants, the volume concentration and mass-volume concentration are commonly used to indicate their content in the atmosphere.

Volume concentration

Volume concentration is expressed as the volume of pollutants in the atmosphere per cubic meter (cubic centimeters) or (ml / m³). The commonly used method is ppm, that is, 1ppm = 1cubic centimeter / cubic meter = 10. In addition to ppm, there are ppb and ppt, and the relationship between them is:

1ppm = 10 = one millionth, 1ppb = 10 = one billionth,

1ppt = 10¹² = one trillion, 1ppm = 10 ³ ppb = 10 ⁶ ppt

Volume percentage concentration

The volume (ml) of the solute contained in a 100ml solution, such as 95% ethanol, is to make up 95ml ethanol with water to 100mL (due to the molecular volume, the volume of the solution obtained by adding 95mL ethanol to 5mL water is less than 100mL, so the volume percentage concentration is generally It can only reflect the volume of the solute. Depending on the solution, the volume of the solute solvent cannot be simply added).

concentration

If the concentration is very thin, it can also be expressed in ppm and ppb. 1ppm = 1mg L, 1ppb = 1ng L.

Mass percentage concentration

The concentration expressed as the percentage of the mass of the solute in the total mass of the solution is called the mass percentage concentration (abbreviated as the percentage concentration). Mass percentage concentration is a concentration commonly used in daily life and production, and it has no dimension. It will be legally measured in the future

Unit mass fraction (W) instead. The mass fraction WB of substance B is the ratio of the mass of substance B to the mass of the mixture. For example, 5g of sodium chloride is dissolved in 95g of water to make a 100g solution. Its mass percentage concentration is 5%, and its mass fraction is 0.05 or 5 × 10². 0.9% physiological saline is used for medical purposes, 0.9% is the mass-volume percentage concentration. What it means is that 0.9 g of sodium chloride is dissolved in water to make a 100 mL solution.

Baume degree (° Bé) is a way to express the concentration of a solution. When the Baume hydrometer is immersed in the measured solution, the degree obtained is called Baume degree. Baume is named after French chemist Antoine Baume. Baume was a pharmacy apprentice and was a professor at the Paris Academy of Pharmacy. He created a hydrometer, the Baume Hydrometer.

Baume Hydrometer

There are two types: a weight gauge for measuring liquids heavier than water; and a light gauge for measuring liquids lighter than water. When the Baume degree is measured, the concentration percentage of the solution can be conveniently found from the comparison table of the corresponding chemistry manual. For example, the Baume degree of concentrated sulfuric acid measured at 15 ° C is 66 ° Bé. Checking the table shows that the mass percentage concentration of sulfuric acid is 98%.

The value of Baume degree is large and the reading is convenient, so Baume degree is often used in production to indicate the concentration of a solution (a solution with a certain concentration has a certain density or specific gravity).

concentration

The methods for measuring the Baume degree of different solutions are similar. They are all based on the method of measuring specific gravity. According to the measured specific gravity, check the table to convert the concentration. Since 2011, Baume watches for different solutions have been dedicated, such as alcohol Baume watches and salt water Baume watches. On this Baume watch, the concentration of the solution corresponding to the solution Baume degree can be directly read No need to look up the table.

Baume degree and specific gravity conversion method

Baume degree = 144.3- (144.3 / specific gravity); Specific gravity = 144.3 / (144.3- Baume degree)

For lighter than water: specific gravity = 144.3 / (144.3 + Baume degree)

In general, Baume hydrometers should be measured at a temperature of 15.6 degrees, but the temperature usually does not meet the standard in actual use, so it needs to be calibrated. Generally speaking, every time the temperature differs by 1 degree, the Baume meter differs by 0.054 degrees. Increase when the temperature is higher than the standard, and decrease when the temperature is lower.