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1 gram per cubic meter [g/m³] = 1 milligram per liter [mg/l]

Initial value

Converted value

kilogram per cubic meter kilogram per cubic centimeter gram per cubic meter gram per cubic centimeter gram per cubic millimeter milligram per cubic meter milligram per cubic centimeter milligram per cubic millimeter exagram per liter petagram per liter teragram per liter gigagram per liter megagram per liter kilogram per liter hectogram per liter decagram per liter gram per liter decigram per liter centigram per liter milligram per liter microgram per liter nanogram per liter picogram per liter femtogram per liter attogram per liter pound per cubic inch pound per cubic foot pound per cubic yard pound per gallon (US) ) pound per gallon (UK) ounce per cubic inch ounce per cubic foot ounce per gallon (US) ounce per gallon (UK) grain per gallon (US) grain per gallon (UK) grain per cubic foot short ton per cubic foot yard long ton per cubic yard slug per cubic foot Earth's average density slug per cubic inch slug per cubic yard Plankowska i density

The principle of operation of the Geiger counter

More about density

General information

Density is a property that determines the amount of a substance by mass per unit volume. In the SI system, density is measured in kg / m³, but other units are also used, such as g / cm³, kg / l and others. In everyday life, two equivalent values ​​\u200b\u200bare most often used: g / cm³ and kg / ml.

Factors affecting the density of matter

The density of the same substance depends on temperature and pressure. Generally, the higher the pressure, the tighter the molecules are packed, which increases the density. In most cases, an increase in temperature, on the contrary, increases the distance between molecules and reduces the density. In some cases, this relationship is reversed. The density of ice, for example, is less than that of water, even though ice is colder than water. This can be explained by the molecular structure of ice. Many substances, when moving from a liquid to a solid state of aggregation, change their molecular structure so that the distance between molecules decreases, and the density, respectively, increases. During the formation of ice, the molecules line up in a crystal structure and the distance between them, on the contrary, increases. In this case, the attraction between the molecules also changes, the density decreases, and the volume increases. In winter, you must not forget about this property of ice - if the water in the water pipes freezes, then they can break.

Density of water

If the density of the material from which the object is made is greater than the density of water, then it is completely immersed in water. Materials with a density less than that of water, on the contrary, float to the surface. A good example is ice, which is less dense than water and floats in a glass to the surface of water and other drinks that are mostly water. We often use this property of substances in everyday life. For example, in the construction of ship hulls, materials with a density higher than that of water are used. Since materials with a density higher than that of water sink, air-filled cavities are always created in the ship's hull, since the density of air is much lower than that of water. On the other hand, sometimes it is necessary that the object sink in water - for this, materials with a higher density than water are chosen. For example, in order to sink light bait to a sufficient depth while fishing, anglers tie a sinker made of materials having a high density, such as lead, to the fishing line.

Oil, fat and oil remain on the surface of the water because their density is lower than that of water. Thanks to this property, oil spilled in the ocean is much easier to clean up. If it mixed with water or sank to the seabed, it would cause even more damage to the marine ecosystem. This property is also used in cooking, but not oil, of course, but fat. For example, it is very easy to remove excess fat from soup as it floats to the surface. If the soup is cooled in the refrigerator, the fat solidifies, and it is even easier to remove it from the surface with a spoon, slotted spoon, or even a fork. In the same way, it is removed from jelly and aspic. This reduces the calorie and cholesterol content of the product.

Information about the density of liquids is also used during the preparation of drinks. Layered cocktails are made from liquids of different densities. Typically, lower density liquids are carefully poured onto higher density liquids. You can also use a glass cocktail stick or bar spoon and slowly pour the liquid over them. If you do not rush and do everything carefully, you will get a beautiful multi-layered drink. This method can also be used with jellies or aspic dishes, although if time permits it is easier to cool each layer separately, pouring a new layer only after the bottom layer has hardened.

In some cases, a lower fat density, on the contrary, interferes. Products with a high fat content often do not mix well with water and form a separate layer, thus impairing not only the appearance, but also the taste of the product. For example, in cold desserts and fruit smoothies, fatty dairy products are sometimes separated from non-fat dairy products such as water, ice, and fruit.

Salt water density

The density of water depends on the content of impurities in it. In nature and in everyday life, pure H 2 O water without impurities is rarely found - most often it contains salts. A good example is sea water. Its density is higher than that of fresh water, so fresh water usually "floats" on the surface of salt water. Of course, it is difficult to see this phenomenon under normal conditions, but if fresh water is enclosed in a shell, for example, in a rubber ball, then this is clearly visible, since this ball floats to the surface. Our body is also a kind of shell filled with fresh water. We are made up of 45% to 75% water - this percentage decreases with age and with an increase in weight and body fat. Fat content of at least 5% of body weight. Healthy people have up to 10% body fat if they exercise a lot, up to 20% if they are of normal weight, and 25% or more if they are obese.

If we try not to swim, but simply to stay on the surface of the water, we will notice that it is easier to do this in salt water, since its density is higher than the density of fresh water and the fat contained in our body. The concentration of salt in the Dead Sea is 7 times the average concentration of salt in the oceans of the world, and it is known throughout the world for the fact that people can easily float on the surface of the water and not drown. Although, to think that it is impossible to die in this sea is a mistake. In fact, every year people die in this sea. The high salt content makes water dangerous if it enters the mouth, nose, and eyes. If you swallow such water, you can get a chemical burn - in severe cases, such unfortunate swimmers are hospitalized.

Air density

Just as in the case of water, bodies with a density below that of air are positively buoyant, that is, they take off. A good example of such a substance is helium. Its density is 0.000178 g/cm³, while the density of air is approximately 0.001293 g/cm³. You can see how helium takes off in the air if you fill a balloon with it.

The density of air decreases as its temperature increases. This property of hot air is used in balloons. The balloon pictured in the ancient Mayan city of Teotihuocán in Mexico is filled with hot air that has a density less than that of the surrounding cold morning air. That is why the ball flies at a sufficiently high altitude. While the ball flies over the pyramids, the air in it cools down, and it is heated again with a gas burner.

Density calculation

Often the density of substances is indicated for standard conditions, that is, for a temperature of 0 ° C and a pressure of 100 kPa. In educational and reference manuals, you can usually find such a density for substances that are often found in nature. Some examples are shown in the table below. In some cases, the table is not enough and the density must be calculated manually. In this case, the mass is divided by the volume of the body. Mass is easy to find with a balance. To find out the volume of a standard geometric body, you can use formulas to calculate the volume. The volume of liquids and solids can be found by filling the measuring cup with the substance. For more complex calculations, the liquid displacement method is used.

Liquid displacement method

To calculate the volume in this way, first pour a certain amount of water into a measuring vessel and place the body, the volume of which must be calculated, until completely immersed. The volume of a body is equal to the difference between the volume of water without the body and with it. It is believed that this rule was derived by Archimedes. It is possible to measure volume in this way only if the body does not absorb water and does not deteriorate from water. For example, we will not measure the volume of a camera or fabric using the liquid displacement method.

It is not known how much this legend reflects real events, but it is believed that King Hieron II gave Archimedes the task of determining whether his crown was made of pure gold. The king suspected that his goldsmith had stolen some of the gold allocated for the crown and instead made the crown out of a cheaper alloy. Archimedes could easily determine this volume by melting the crown, but the king ordered him to find a way to do this without damaging the crowns. It is believed that Archimedes found the solution to this problem while taking a bath. Having plunged into the water, he noticed that his body displaced a certain amount of water, and realized that the volume of water displaced is equal to the volume of the body in water.

hollow bodies

Some natural and artificial materials are made up of particles that are hollow inside, or of particles so small that these substances behave like liquids. In the second case, an empty space remains between the particles, filled with air, liquid, or other substance. Sometimes this place remains empty, that is, it is filled with vacuum. Examples of such substances are sand, salt, grain, snow and gravel. The volume of such materials can be determined by measuring the total volume and subtracting from it the volume of voids determined by geometric calculations. This method is convenient if the shape of the particles is more or less uniform.

For some materials, the amount of empty space depends on how tightly packed the particles are. This complicates the calculations, since it is not always easy to determine how much empty space there is between particles.

Table of densities of commonly occurring substances in nature

Density and Mass

In some industries, such as aviation, it is necessary to use materials that are as light as possible. Since low density materials also have low mass, in such situations, try to use materials with the lowest density. So, for example, the density of aluminum is only 2.7 g/cm³, while the density of steel is from 7.75 to 8.05 g/cm³. It is due to the low density that 80% of aircraft bodies use aluminum and its alloys. Of course, at the same time, one should not forget about strength - today, few people make aircraft from wood, leather, and other light but low-strength materials.

In aircraft, composite materials are often used instead of pure metals, since, unlike metals, such materials have high elasticity at low weight. The propellers of this Bombardier Q400 aircraft are made entirely of composite materials.

Black holes

On the other hand, the higher the mass of a substance per given volume, the higher the density. Black holes are an example of physical bodies with a very small volume and a huge mass, and, accordingly, a huge density. Such an astronomical body absorbs light and other bodies that are close enough to it. The largest black holes are called supermassive.

Do you find it difficult to translate units of measurement from one language to another? Colleagues are ready to help you. Post a question to TCTerms and within a few minutes you will receive an answer.

At analysis of mixtures of various gases in order to determine their qualitative and quantitative composition, use the following basic units of measurement:
- "mg / m 3";
- "ppm" or "million -1";
- "% about. d.”;
- "% NKPR".

The mass concentration of toxic substances and the maximum permissible concentration (MPC) of combustible gases is measured in "mg / m 3".
The unit of measurement "mg / m 3" (eng. "mass concentration") is used to indicate the concentration of the measured substance in the air of the working area, the atmosphere, as well as in the exhaust gases, expressed in milligrams per cubic meter.
When performing gas analysis, it is common for end users to convert gas concentrations from "ppm" to "mg/m3" and vice versa. This can be done using our Gas Units Calculator.

The million fraction of gases and various substances is a relative value and is indicated in ppm or ppm.
"ppm" (English "parts per million" - "parts per million") - a unit of measurement for the concentration of gases and other relative values, similar in meaning to ppm and percent.
The unit "ppm" (ppm) is convenient to use for assessing low concentrations. One ppm is one part per 1,000,000 parts and has a value of 1×10 -6 of the baseline.

The most common unit for measuring the concentration of combustible substances in the air of the working area, as well as oxygen and carbon dioxide, is the volume fraction, which is denoted by the abbreviation “% vol. etc." .
"% about. etc." - is a value equal to the ratio of the volume of any substance in the gas mixture to the volume of the entire gas sample. The volume fraction of gas is usually expressed as a percentage (%).

"% LEL" (LEL - English Low Explosion Level) - the lower concentration limit of flame distribution, the minimum concentration of a combustible explosive in a homogeneous mixture with an oxidizing environment at which an explosion is possible.

MAXIMUM PERMISSIBLE CONCENTRATIONS, MPC harmful substances in the air of the working area - concentrations that, during daily (except weekends) work of any productivity, but not more than 41 hours a week, during the entire working experience cannot cause diseases or deviations in the state of health detected by modern research methods in the process work or in the long-term life of present and subsequent generations See Appendix 3. GOST 12.1.005-76.

Maximum allowable concentrations of certain substances

1. 1. Unity of measurements and control: units of measurement ppm, mg/m3 and MPC.

Current systems of measurement units for air quality parameters.

1.1. General definition of PPM.

For the determination of air quality parameters, the main units of measurement are the volume or mass fraction of the main air components, the volume fraction of gaseous pollutants, the mole fraction of gaseous pollutants, expressed respectively as a percentage, parts per million (ppm), parts per billion (ppb), as well as mass concentration of gaseous pollutants , expressed in mg / m 3 or μg / m 3. According to the standards, the use of relative units (ppm and ppb) and absolute units (mg/m 3 and µg/m 3) is allowed when reporting measurement results in the field of air quality control. Here are some definitions:

PPM, as well as percentage, ppm - a dimensionless ratio of a physical quantity to a value of the same name, taken as the initial one (for example, the mass fraction of a component, the mole fraction of a component, the volume fraction of a component).

PPM is a value determined by the ratio of the measured entity (substance) to one millionth of the total, which includes the measured substance.

PPM has no dimension, since it is a relative value, and is convenient for estimating small fractions, since it is less than a percentage (%) by 10,000 times.

"PPMv(parts per million by volume) is a unit of concentration in parts per million by volume, i.e. the ratio of a volume fraction to everything (including this fraction). PPMw(parts per million by weight) is a unit of concentration in parts per million by weight (sometimes called "by weight"). Those. the ratio of mass fraction to everything (including this fraction). Note that in most cases, the undefined unit is "PPM" - for gas mixtures it is PPMv, and for solutions and dry mixtures it is PPMw. Be careful, because with a definition error, you may not even get into the order of magnitude. This link is to the ENGINEERING Handbook. . http://www.dpva.info/Guide/

1.2. PPM in gas analysis.

Let us return once again to the general definition of PPM as the ratio of the number of some units of measurement of a part (share) to one millionth of the total number of the same units as a whole. In gas analysis, such a unit is often the number of moles of a substance

where m is the mass of the chemical pollutant (PCS) in the air when measuring concentration, and M is the molar mass of this substance. The number of moles is a dimensionless quantity; it is an important parameter of Mendeleev's law for ideal gases. With this definition, the mole is a universal unit of the amount of a substance, more convenient than the kilogram.

1.3. How are concentration units in ppm and mg/m3 related?

We quote from the text:

“Note that concentration units, denoted as ppm (parts per million), are quite widespread; in relation to the concentration of any substance in the air; ppm should be understood as the number of kilomoles of this substance that falls on 1 million kilomoles of air. (Here a translation error was made: it should read 1 millionth of a kilomole). Further:

"To convert ppm to mg/m

ρ air (under normal conditions 1.2 kg / m 3). Then

C [mg / m 3] \u003d C * M zhv / (M air / ρ air) \u003d C * M zhv / 24.2 "(1)

Let us explain the above formula for recalculating concentrations.

Here С[mg/m 3 ] is the concentration of HCV at the measurement point with meteorological parameters: temperature T and pressure P, and M air /ρ air = 24.2 is the standard parameter.

The question arises: when calculating the standard parameter (M air / ρ air) \u003d 24.2 and air density ρ (1.2 kg / m 3), what values ​​​​of the parameters T 0 and P 0 were used, taken as "normal conditions"? Since for true normal conditions

T \u003d 0 0 C, and 1 atm. ρ 0 air = 1.293 and M air = 28.98, (M air / ρ 0 air) = 28.98: 1.293 = 22.41 = V 0 (molar volume of an ideal gas), we calculate the value of “normal temperature” in (1) using the formula for reducing the density parameter [ 3]:

ρ air \u003d ρ 0 air * f, \u003d ρ 0 air * f \u003d P 1 T 0 / P 0 T 1, (2)

where f is the standard normalization conversion factor . ρ air = M air: 24.2 = 1.2,

f = ρ air: ρ 0 air = 1.2: 1.293 = 0.928, which corresponds to the measurement conditions

t \u003d 20 0 C, P 0 \u003d 760 mm Hg. Art. Therefore, in the report and the conversion formula (1), it is customary to consider T 0 \u003d 20 0 C, P 0 \u003d 760 mm Hg as normal conditions. Art.

1.4. What definition of concentration in ppm units is used in the EU-Russia Program report.

The question that needs to be clarified is the following: what is the definition of ppm taken as a basis in: the ratio by volume, by mass or by moles? Let us show further that the third option holds. This is important to understand because it is a report

According to the international program “EU-Russia. Harmonization of environmental standards” and the preamble to the report states the need to discuss the submitted materials.

We will rewrite formula (1) for the reverse calculation:

C \u003d (C [mg / m 3] * M air) / (ρ air * M zhv) \u003d

(C [mg / m 3] / M zhv) / (ρ air / M air) \u003d k * C [mg / m 3] * / M zhv,

where k = M air / ρ air = 29. / 1.2 = 24.2 (2’)

In the formula (2'), the relative concentration C is the ratio of the number of moles of impurity (MHV) and air under normal conditions. Let us explain this statement based on the definition of PPMw:

Cw \u003d n / (n 0 / 10 6) \u003d 10 6 n / n 0 (3)

n is the number of kilomoles of the WCV in a certain volume under the conditions of measurement,

n 0 - the number of kilomoles of air under normal conditions in the same volume.

Since n= m / M * zxv and n 0 = m 0 / M * 0, where M * zxv and M * 0

molar masses of the pollutant and air, we obtain the expression for Cw:

Cw \u003d 10 6 (m / M * wxv) / (m 0 / M * 0) \u003d

10 6 ((m / V 0) / M * zxv) / ((m 0 / V 0) / M * 0) \u003d 10 6 (C zshv / M * zhv) / (C 0 / M * 0), ( four),

where V 0 is the molar volume of air.

Expression (4) coincides with the reduction formula (2),

since (m / V 0) \u003d C wxv \u003d 10 6 C [mg / m 3] and (m 0 / V 0) \u003d C 0 \u003d ρ air

(under normal conditions 1.2 kg / m 3), V 0 \u003d 22.4 [l] and M 0 \u003d M air \u003d 29 [kg], which proves our statement about the determination of Cw.

1.5 Let's consider one more definition of PPM for the analysis of CW in air in accordance with the general definition, namely: ppm meas = Cw meas:

Cw meas = 10 6 n zhv / n air , where (5)

n meas - the number of kilomoles of the WXV in a certain volume under the conditions of measurement,

n air \u003d - the number of kilomoles of air under measurement conditions in the same volume.

Formula (4) for measuring ppm in this case takes the form:

Cw meas \u003d 10 6 (C zhv / M * zhv) / (C air / M * 0) (5 ')

The air concentration at the measurement point C air \u003d m air / V 0 is related to its density (concentration) by expression (2): FROM air = C 0 * f , C air = ρ air . (2’)

Substituting (2') into (5'), we get (because (С zxv / f) = С 0 zxv) :

Cw meas \u003d 10 6 (C wxv / M * wxv) / (C 0 * f / M * 0) \u003d 10 6 ((C wxw / f) / M * wxw) / (C 0 / M * 0) \u003d C 0w,

which is the normative value of ppm, reduced to normal conditions.

Therefore, introduced by definition 1.5 Cw meas coincides with C 0 w and it does not require any correction to bring it to normal conditions, since it is identical to it. The conclusion is quite obvious, since the ratio of the measured WCV and air under the same measurement conditions is used.

It is important to note that in the standard concerning the verification scheme for measuring instruments for components in gaseous media, it is shown that a unit of mole fraction or mass concentration of components is transmitted from working standards of various capacity to measuring instruments of all types, designed to assess the quality of atmospheric air and the air of the working area.

In the section on the question Conversion of volume % to mg/m3 given by the author Snooki the best answer is You need to convert 0.95% by volume of H2S in air to milligrams per cubic meter, right? So it's easier than a steamed turnip ...
You will have 1000 * 0.0095 = 9.5 liters of hydrogen sulfide in a cubic meter.
Molar mass of hydrogen sulfide: 32+2*1=34 g/mol.
The molar volume of any gas at n. y. 22.4 liters.
So, you have 9.5 * 34 / 22.4 = 14.4 grams of hydrogen sulfide in a cubic meter, or 14400 mg / m ^ 3 - this is a FUCKING DANGEROUS CONCENTRATION. A few breaths (and one is enough for someone!) - and into the next world. Even 10 times lower concentration (0.1%) leads a person to death in 10 minutes))
Divergent
Higher intelligence
(831042)
The volume when converting the concentration from volume percent to milligrams per cubic meter is completely unnecessary, it's just that your chemistry is seriously bad ...
Yes, they breathe, only MPC in the working area is not more than 10 mg/m^3. And you have indicated a concentration of almost one and a half thousand times more than the MPC. This is an "almost instantaneous" lethal concentration.