molar concentration. What does molar and molal concentration mean? Education in the Volga region

It can be expressed both in dimensionless units (fractions, percentages) and in dimensional quantities (mass fractions, molarity, titers, mole fractions).

Concentration is the quantitative composition of the solute (in specific units) per unit volume or mass. The solute is named X, and the solvent - S. Most often I use the concept of molarity (molar concentration) and mole fraction.

1. (or percentage concentration of a substance) is the ratio of the mass of a solute m to the total mass of the solution. For a binary solution consisting of a solute and a solvent:

ω - mass fraction of the dissolved substance;

m in-va- mass of dissolved substance;

mr-ra is the mass of the solvent.

The mass fraction is expressed in fractions of a unit or as a percentage.

2. Molar concentration or molarity is the number of moles of a solute in one liter of solution V:

C- molar concentration of a dissolved substance, mol / l (it is also possible to designate M, for example, 0.2 MHCl);

V- the volume of the solution, l.

The solution is called molar or unimolar, if 1 mole of a substance is dissolved in 1 liter of solution, decimolar- 0.1 mol of substance is dissolved, centomolar- 0.01 mol of substance is dissolved, millimolar- 0.001 mol of a substance is dissolved.

3. Molar concentration(molality) of solution C(x) shows the number of moles n solute in 1 kg of solvent m:

C(x) - molality, mol/kg;

n- amount of dissolved substance, mol;

mr-la- mass of solvent, kg.

4. - substance content in grams in 1 ml of solution:

T- titer of dissolved substance, g/ml;

m in-va- mass of the dissolved substance, g;

V r-ra- volume of solution, ml.

5. - dimensionless quantity, equal to the ratio amount of solute n to the total amount of substances in solution:

N- molar fraction of the dissolved substance;

n- amount of dissolved substance, mol;

n r-la- the amount of solvent substance, mol.

The sum of the mole fractions must equal 1:

N(X) + N(S) = 1.

where N(X) X;

N(S) - mole fraction of solute S.

Sometimes, when solving problems, it is necessary to move from one unit of expression to another:

ω(X) - mass fraction of the dissolved substance, in%;

M(X) is the molar mass of the solute;

ρ = m/(1000 V) is the density of the solution.6. - the number of gram equivalents of a given substance in one liter of solution.

Gram equivalent of substance- the number of grams of a substance, numerically equal to its equivalent.

Equivalent- this is a conventional unit, equivalent to one hydrogen ion in acid-base reactions or one electron in redox reactions.

Abbreviations are used to record the concentration of such solutions. n or N. For example, a solution containing 0.1 mol-eq / l is called decinormal and is written as 0.1 n.

C N- normal concentration, mol-eq/l;

z- equivalence number;

V r-ra- the volume of the solution, l.

Solubility substances S - the maximum mass of a substance that can be dissolved in 100 g of a solvent:

Solubility factor- the ratio of the mass of the substance forming saturated solution at a specific temperature, to the mass of the solvent:

Length and Distance Converter Mass Converter Bulk Solids and Foods Volume Converter Area Converter Volume and Units Converter recipes Temperature Converter Pressure, Stress, Young's Modulus Converter Energy and Work Converter Power Converter Force Converter Time Converter Linear Speed Converter Flat Angle Thermal Efficiency and Fuel Efficiency Converter Numeral Converter Converter of Units of Measurement of Quantity of Information Currency Rates Women's Clothing and Shoe Sizes Sizes Men's Clothing and Shoes Converter angular velocity and Speed Converter Acceleration Converter Angular Acceleration Converter Density Converter Specific Volume Converter Moment of Inertia Converter Moment of Force Converter Torque Converter Specific calorific value (by mass) converter Energy density and specific calorific value (by volume) converter Temperature difference converter Thermal expansion coefficient converter Converter Thermal Resistance Thermal Conductivity Converter Specific Heat Converter Energy Exposure and Power Converter thermal radiation Density converter heat flow Heat Transfer Coefficient Converter Volume Flow Converter Mass Flow Converter Molar Flow Converter Mass Flux Density Converter Molar Concentration Converter Mass Solution Mass Concentration Converter Dynamic (Absolute) Viscosity Converter Kinematic Viscosity Converter Surface Tension Converter Vapor Permeability Converter Water Vapor Flux Density Converter Sound Level Converter Microphone Sensitivity Converter Converter sound pressure level (SPL) Sound pressure level converter with selectable reference pressure Brightness converter Luminous intensity converter Illuminance converter Computer graphics resolution converter Frequency and wavelength converter Power in diopters and focal length Power in diopters and lens magnification (×) Converter electric charge Linear Charge Density Converter Surface Charge Density Converter Volumetric Charge Density Converter Electric Current Converter Linear Current Density Converter Surface Current Density Converter Tension Converter electric field Electrostatic Potential and Voltage Converter Electrical Resistance Converter Electrical Resistivity Converter Electrical Conductivity Converter Electrical Conductivity Converter Capacitance Inductance Converter American Wire Gauge Converter Levels in dBm (dBm or dBmW), dBV (dBV), Watts, etc. tension magnetic field Converter magnetic flux Magnetic Induction Converter Radiation. Ionizing Radiation Absorbed Dose Rate Converter Radioactivity. Radioactive Decay Converter Radiation. Exposure Dose Converter Radiation. Absorbed dose converter Periodic system chemical elements D. I. Mendeleev

1 mol per liter [mol/l] = 1000 mol per meter³ [mol/m³]

Initial value

Converted value

moles per meter³ moles per liter moles per centimeter³ moles per millimeters decimeter molar millimolar micromolar nanomolar picomolar femtomolar attomolar zeptomolar yoctomolar

More about molar concentration

General information

The concentration of a solution can be measured in many ways, such as the ratio of the mass of the solute to the total volume of the solution. In this article, we will look at molar concentration, which is measured as the ratio between the amount of substance in moles to the total volume of the solution. In our case, a substance is a soluble substance, and we measure the volume for the entire solution, even if other substances are dissolved in it. Amount of substance is the number of elementary constituents, such as atoms or molecules of a substance. Since even in a small amount of a substance usually big number elementary components, then special units, moles, are used to measure the amount of a substance. One mole is equal to the number of atoms in 12 g of carbon-12, that is, it is approximately 6 × 10²³ atoms.

It is convenient to use moths if we are working with an amount of a substance so small that its amount can be easily measured with home or industrial devices. Otherwise, one would have to work with very big numbers, which is inconvenient, or with a very small weight or volume that is difficult to find without specialized laboratory equipment. Atoms are most often used when working with moles, although other particles, such as molecules or electrons, can also be used. It should be remembered that if not atoms are used, then this must be indicated. Sometimes molar concentration is also called molarity.

Molarity should not be confused with molality. Unlike molarity, molality is the ratio of the amount of solute to the mass of the solvent, and not to the mass of the entire solution. When the solvent is water and the amount of solute is small compared to the amount of water, then molarity and molality are similar in meaning, but otherwise they usually differ.

Factors affecting molar concentration

The molar concentration depends on temperature, although this dependence is stronger for some and weaker for other solutions, depending on what substances are dissolved in them. Some solvents expand with increasing temperature. In this case, if the substances dissolved in these solvents do not expand with the solvent, then the molar concentration of the entire solution decreases. On the other hand, in some cases, with increasing temperature, the solvent evaporates, and the amount of the solute does not change - in this case, the concentration of the solution will increase. Sometimes the opposite happens. Sometimes a change in temperature affects how a solute dissolves. For example, some or all of the solute ceases to dissolve and the concentration of the solution decreases.

Units

Molar concentration is measured in moles per unit volume, such as moles per liter or moles per cubic meter. Moles per cubic meter is an SI unit. Molarity can also be measured using other units of volume.

How to find molar concentration

To find the molar concentration, you need to know the amount and volume of a substance. The amount of a substance can be calculated using the chemical formula of that substance and information about the total mass of that substance in solution. That is, to find out the amount of the solution in moles, we find out from the periodic table the atomic mass of each atom in the solution, and then we divide the total mass of the substance by the total atomic mass of the atoms in the molecule. Before adding together the atomic mass, make sure that we multiply the mass of each atom by the number of atoms in the molecule we are considering.

You can also do the calculations in reverse order. If the molar concentration of the solution and the formula of the solute are known, then you can find out the amount of solvent in the solution, in moles and grams.

Examples

Find the molarity of a solution of 20 liters of water and 3 tablespoons of soda. In one tablespoon - about 17 grams, and in three - 51 grams. Baking soda is sodium bicarbonate whose formula is NaHCO₃. In this example, we'll use atoms to calculate molarity, so we'll find the atomic masses of the sodium (Na), hydrogen (H), carbon (C), and oxygen (O) constituents.

Na: 22.989769
H: 1.00794
C: 12.0107
O:15.9994

Since the oxygen in the formula is O₃, it is necessary to multiply the atomic mass of oxygen by 3. We get 47.9982. Now add the masses of all atoms and get 84.006609. The atomic mass is indicated in the periodic table in atomic mass units, or a. e. m. Our calculations are also in these units. One a. e.m. is equal to the mass of one mole of a substance in grams. That is, in our example, the mass of one mole of NaHCO₃ is 84.006609 grams. In our task - 51 grams of soda. We find the molar mass by dividing 51 grams by the mass of one mole, that is, by 84 grams, and we get 0.6 moles.

It turns out that our solution is 0.6 moles of soda dissolved in 20 liters of water. We divide this amount of soda by the total volume of the solution, that is, 0.6 mol / 20 l \u003d 0.03 mol / l. Since the solution used a large number of solvent and a small amount of solute, then its concentration is low.

Let's consider another example. Find the molar concentration of one sugar cube in a cup of tea. Table sugar is made up of sucrose. First, let's find the weight of one mole of sucrose, the formula of which is C₁₂H₂₂O₁₁. Using the periodic table, we find atomic masses and determine the mass of one mole of sucrose: 12 × 12 + 22 × 1 + 11 × 16 = 342 grams. There are 4 grams of sugar in one cube of sugar, which gives us 4/342 = 0.01 moles. There are about 237 milliliters of tea in one cup, so the concentration of sugar in one cup of tea is 0.01 moles / 237 milliliters × 1000 (to convert milliliters to liters) = 0.049 moles per liter.

Application

Molar concentration is widely used in calculations related to chemical reactions. The branch of chemistry that calculates the ratios between substances in chemical reactions and often works with moles is called stoichiometry. The molar concentration can be found from chemical formula final product, which then becomes soluble substance, as in the example with a soda solution, but you can also first find this substance by the formulas of the chemical reaction during which it is formed. To do this, you need to know the formulas of the substances involved in this chemical reaction. Having solved the chemical reaction equation, we find out the formula of the molecule of the solute, and then we find the mass of the molecule and the molar concentration using the periodic table, as in the examples above. Of course, it is possible to perform calculations in reverse order, using information about the molar concentration of a substance.

Let's consider a simple example. This time we will mix baking soda with vinegar to see an interesting chemical reaction. Both vinegar and baking soda are easy to find - you probably have them in your kitchen. As mentioned above, the formula for baking soda is NaHCO₃. Vinegar is not pure substance, and 5% solution of acetic acid in water. The formula for acetic acid is CH₃COOH. The concentration of acetic acid in vinegar can be more or less than 5%, depending on the manufacturer and the country in which it is made, since in different countries concentration of vinegar is different. In this experiment, you do not have to worry about the chemical reactions of water with other substances, since water does not react with soda. We only care about the volume of water when we later calculate the concentration of the solution.

First, we solve the equation for the chemical reaction between soda and acetic acid:

NaHCO₃ + CH₃COOH → NaC₂H₃O₂ + H₂CO₃

The reaction product is H₂CO₃, a substance that, due to low stability, enters into a chemical reaction again.

H₂CO₃ → H₂O + CO₂

As a result of the reaction, we get water (H₂O), carbon dioxide(CO₂) and sodium acetate (NaC₂H₃O₂). We mix the resulting sodium acetate with water and find the molar concentration of this solution, just as before we found the concentration of sugar in tea and the concentration of soda in water. When calculating the volume of water, it is necessary to take into account the water in which acetic acid is dissolved. sodium acetate - interesting substance. It is used in chemical heating pads, such as hand warmers.

Using stoichiometry to calculate the amount of substances that enter into a chemical reaction, or reaction products, for which we will later find the molar concentration, it should be noted that only a limited amount of a substance can react with other substances. This also affects the amount of the final product. If the molar concentration is known, then, on the contrary, it is possible to determine the amount of starting products by the reverse calculation method. This method is often used in practice, in calculations related to chemical reactions.

When using recipes, whether in cooking, in making medicines, or in creating the ideal environment for aquarium fish, it is necessary to know the concentration. IN Everyday life most often it is more convenient to use grams, but in pharmaceuticals and chemistry, molar concentration is more often used.

In pharmaceuticals

When creating drugs, the molar concentration is very important, since it determines how the drug affects the body. If the concentration is too high, then the drugs can even be fatal. On the other hand, if the concentration is too low, then the drug is ineffective. In addition, concentration is important in the exchange of fluids across cell membranes in the body. When determining the concentration of a liquid that must either pass or, conversely, not pass through the membranes, either the molar concentration is used, or it is used to find osmotic concentration. Osmotic concentration is used more often than molar concentration. If the concentration of a substance, such as a drug, is higher on one side of the membrane than on the other side of the membrane, such as inside the eye, then the more concentrated solution will move across the membrane to where the concentration is lower. This flow of solution across the membrane is often problematic. For example, if fluid moves into the interior of a cell, for example, into a blood cell, then it is possible that due to this overflow of fluid, the membrane will be damaged and rupture. Leakage of fluid from the cell is also problematic, as this will disrupt the performance of the cell. Any drug-induced flow of fluid through the membrane out of or into the cell is desirable to prevent, and to do this, the concentration of the drug is sought to be similar to that of a fluid in the body, such as blood.

It is worth noting that in some cases the molar and osmotic concentrations are equal, but this is not always the case. It depends on whether the substance dissolved in water has broken down into ions in the process electrolytic dissociation . When calculating the osmotic concentration, particles in general are taken into account, while when calculating the molar concentration, only certain particles, such as molecules, are taken into account. Therefore, if, for example, we are working with molecules, but the substance has broken up into ions, then there will be fewer molecules total number particles (including both molecules and ions), and hence the molar concentration will be lower than the osmotic one. To convert molar concentration to osmotic concentration, you need to know physical properties solution.

In the manufacture of medicines, pharmacists also take into account tonicity solution. Tonicity is a property of a solution that depends on concentration. Unlike osmotic concentration, tonicity is the concentration of substances that the membrane does not let through. The process of osmosis causes solutions with a higher concentration to move into solutions with a lower concentration, but if the membrane prevents this movement by not passing the solution through, then there is pressure on the membrane. Such pressure is usually problematic. If a drug is intended to enter the blood or other body fluid, then the tonicity of the drug must be balanced against the tonicity of the body fluid to avoid osmotic pressure on the membranes in the body.

To balance tonicity, drugs are often dissolved in isotonic solution. An isotonic solution is a solution of table salt (NaCL) in water at a concentration that balances the tonicity of the fluid in the body and the tonicity of the mixture of this solution and the drug. Usually isotonic solution is stored in sterile containers and infused intravenously. Sometimes it is used in its pure form, and sometimes - as a mixture with medicine.

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.

One of the basic units in the International System of Units (SI) is the unit of quantity of a substance is the mole.

mole – is the amount of a substance that contains so much structural units of a given substance (molecules, atoms, ions, etc.), how many carbon atoms are contained in 0.012 kg (12 g) of a carbon isotope 12 FROM .

Given that the value of the absolute atomic mass for carbon is m(C) \u003d 1.99 10  26 kg, you can calculate the number of carbon atoms N BUT contained in 0.012 kg of carbon.

A mole of any substance contains the same number of particles of this substance (structural units). The number of structural units contained in a substance with an amount of one mole is 6.02 10 23 and called Avogadro's number (N BUT ).

For example, one mole of copper contains 6.02 10 23 copper atoms (Cu), and one mole of hydrogen (H 2) contains 6.02 10 23 hydrogen molecules.

molar mass(M) is the mass of a substance taken in an amount of 1 mol.

The molar mass is denoted by the letter M and has the unit [g/mol]. In physics, the dimension [kg/kmol] is used.

In general numerical value molar mass of a substance numerically coincides with the value of its relative molecular (relative atomic) mass.

For example, relative molecular mass water is equal to:

Mr (H 2 O) \u003d 2Ar (H) + Ar (O) \u003d 2 ∙ 1 + 16 \u003d 18 a.m.u.

The molar mass of water has the same value, but is expressed in g/mol:

M (H 2 O) = 18 g/mol.

Thus, a mole of water containing 6.02 10 23 water molecules (respectively 2 6.02 10 23 hydrogen atoms and 6.02 10 23 oxygen atoms) has a mass of 18 grams. 1 mole of water contains 2 moles of hydrogen atoms and 1 mole of oxygen atoms.

1.3.4. The relationship between the mass of a substance and its quantity

Knowing the mass of a substance and its chemical formula, and hence the value of its molar mass, one can determine the amount of a substance and, conversely, knowing the amount of a substance, one can determine its mass. For such calculations, you should use the formulas:

where ν is the amount of substance, [mol]; m is the mass of the substance, [g] or [kg]; M is the molar mass of the substance, [g/mol] or [kg/kmol].

For example, to find the mass of sodium sulfate (Na 2 SO 4) in the amount of 5 mol, we find:

1) the value of the relative molecular weight of Na 2 SO 4, which is the sum of the rounded values of the relative atomic masses:

Mr (Na 2 SO 4) \u003d 2Ar (Na) + Ar (S) + 4Ar (O) \u003d 142,

2) the value of the molar mass of the substance numerically equal to it:

M (Na 2 SO 4) = 142 g/mol,

3) and, finally, a mass of 5 mol of sodium sulfate:

m = ν M = 5 mol 142 g/mol = 710 g

Answer: 710.

1.3.5. The relationship between the volume of a substance and its quantity

Under normal conditions (n.o.), i.e. at pressure R , equal to 101325 Pa (760 mm Hg), and temperature T, equal to 273.15 K (0 С), one mole of various gases and vapors occupies the same volume, equal to 22.4 l.

The volume occupied by 1 mole of gas or vapor at n.o. is called molar volumegas and has the dimension of a liter per mole.

V mol \u003d 22.4 l / mol.

Knowing the amount gaseous substance (ν ) And molar volume value (V mol) you can calculate its volume (V) under normal conditions:

V = ν V mol,

where ν is the amount of substance [mol]; V is the volume of the gaseous substance [l]; V mol \u003d 22.4 l / mol.

Conversely, knowing the volume ( V) of a gaseous substance under normal conditions, you can calculate its amount (ν) :

Molar and molal concentrations, despite similar titles, the values are different. Their main difference is that when determining the molal concentration, the calculation is made not on the volume of the solution, as in the detection of molarity, but on the mass of the solvent.

General information about solutions and solubility

A homogeneous system is called, which includes a number of components that are independent of each other. One of them is considered a solvent, and the rest are substances dissolved in it. A solvent is the substance that has the most in solution.

Solubility - the ability of a substance to form homogeneous systems with other substances - solutions in which it is in the form of individual atoms, ions, molecules or particles. Concentration is a measure of solubility.

Therefore, solubility is the ability of substances to be distributed uniformly in the form elementary particles throughout the solvent.

True solutions are classified as follows:

by type of solvent - non-aqueous and aqueous;
by type of solute - solutions of gases, acids, alkalis, salts, etc.;
for interaction with electric shock- electrolytes (substances that have electrical conductivity) and non-electrolytes (substances that are not capable of electrical conductivity);
by concentration - diluted and concentrated.

Concentration and ways of expressing it

Concentration is the content (weight) of a substance dissolved in a certain amount (weight or volume) of the solvent or in a certain volume of the entire solution. It is of the following types:

1. Percentage concentration (expressed in%) - it tells how many grams of a solute are contained in 100 grams of a solution.

2. Molar concentration is the number of gram moles per 1 liter of solution. Shows how many gram molecules are contained in 1 liter of a substance solution.

3. Normal concentration is the number of gram equivalents per 1 liter of solution. Shows how many gram equivalents of a solute are contained in 1 liter of solution.

4. The molar concentration shows how much of the solute in moles falls on 1 kilogram of the solvent.

5. Titer determines the content (in grams) of a substance that is dissolved in 1 milliliter of solution.

Molar and molal concentrations are different from each other. Consider their individual characteristics.

Molar concentration

Formula to determine it:

Cv=(v/V), where

V is the total volume of the solution, liter or m 3.

For example, the entry "0.1 M solution of H 2 SO 4" indicates that 0.1 mol (9.8 grams) of sulfuric acid is present in 1 liter of such a solution.

Molar concentration

It should always be taken into account that molar and molar concentrations have completely different meanings.

What is the molal Formula for its definition is as follows:

Cm=(v/m), where

v is the amount of dissolved substance, mol;

m is the mass of the solvent, kg.

For example, writing a 0.2 M NaOH solution means that 0.2 mol of NaOH is dissolved in 1 kilogram of water (in this case, it is a solvent).

Additional formulas required for calculations

A lot of supporting information may be required in order for the molal concentration to be calculated. Formulas that can be useful for solving basic problems are presented below.

Under the amount of matter ν understand a certain number of atoms, electrons, molecules, ions or other particles.

v=m/M=N/N A =V/V m , where:

m is the mass of the compound, g or kg;
M - molar mass, g (or kg) / mol;
N is the number of structural units;
N A is the number of structural units in 1 mole of a substance, Avogadro's constant: 6.02. 10 23 mol - 1;
V is the total volume, l or m 3 ;
V m - molar volume, l / mol or m 3 / mol.

The latter is calculated by the formula:

V m =RT/P, where

R - constant, 8.314 J / (mol. K);
T - gas temperature, K;
P - gas pressure, Pa.

Examples of tasks for molarity and molality. Task #1

Determine the molar concentration of potassium hydroxide in a 500 ml solution. The mass of KOH in solution is 20 grams.

Definition

The molar mass of potassium hydroxide is:

M KOH \u003d 39 + 16 + 1 \u003d 56 g / mol.

We calculate how much is contained in the solution:

ν(KOH) \u003d m / M \u003d 20/56 \u003d 0.36 mol.

We take into account that the volume of the solution should be expressed in liters:

500 ml = 500/1000 = 0.5 liters.

Determine the molar concentration of potassium hydroxide:

Cv (KOH) \u003d v (KOH) / V (KOH) \u003d 0.36 / 0.5 \u003d 0.72 mol / liter.

Task #2

How much sulfur oxide (IV) under normal conditions (i.e. when P = 101325 Pa, and T = 273 K) should be taken in order to prepare a solution of sulfurous acid with a concentration of 2.5 mol / liter with a volume of 5 liters?

Definition

Determine how much is contained in the solution:

ν (H 2 SO 3) \u003d Cv (H 2 SO 3) ∙ V (solution) \u003d 2.5 ∙ 5 \u003d 12.5 mol.

The sulfuric acid production equation is as follows:

SO 2 + H 2 O \u003d H 2 SO 3

According to this:

ν(SO 2) \u003d ν(H 2 SO 3);

ν(SO 2) \u003d 12.5 mol.

Keeping in mind that under normal conditions, 1 mole of gas has a volume of 22.4 liters, we calculate the volume of sulfur oxide:

V (SO 2) \u003d ν (SO 2) ∙ 22.4 \u003d 12.5 ∙ 22.4 \u003d 280 liters.

Task #3

Determine the molar concentration of NaOH in the solution when it is equal to 25.5%, and the density is 1.25 g/ml.

Definition

We take as a sample a solution with a volume of 1 liter and determine its mass:

m (solution) = V (solution) ∙ p (solution) = 1000 ∙ 1.25 = 1250 grams.

We calculate how much alkali is in the sample by mass:

m (NaOH) \u003d (w ∙ m (solution)) / 100% \u003d (25.5 ∙ 1250) / 100 \u003d 319 grams.

Sodium hydroxide is equal to:

We calculate how much is contained in the sample:

v(NaOH) \u003d m / M \u003d 319/40 \u003d 8 mol.

Determine the molar concentration of alkali:

Cv (NaOH) \u003d v / V \u003d 8/1 \u003d 8 mol / liter.

Task #4

10 grams of NaCl salt were dissolved in water (100 grams). Set the concentration of the solution (molal).

Definition

The molar mass of NaCl is:

M NaCl \u003d 23 + 35 \u003d 58 g / mol.

The amount of NaCl contained in the solution:

ν(NaCl) \u003d m / M \u003d 10/58 \u003d 0.17 mol.

In this case, the solvent is water:

100 grams of water \u003d 100/1000 \u003d 0.1 kg of H 2 O in this solution.

The molar concentration of the solution will be equal to:

Cm (NaCl) \u003d v (NaCl) / m (water) \u003d 0.17 / 0.1 \u003d 1.7 mol / kg.

Task #5

Determine the molar concentration of a 15% NaOH alkali solution.

Definition

A 15% alkali solution means that every 100 grams of solution contains 15 grams of NaOH and 85 grams of water. Or that in every 100 kilograms of solution there are 15 kilograms of NaOH and 85 kilograms of water. In order to prepare it, it is necessary to dissolve 15 grams (kilogram) of alkali in 85 grams (kilograms) of H 2 O.

The molar mass of sodium hydroxide is:

M NaOH = 23 + 16 + 1 = 40 g/mol.

Now we find the amount of sodium hydroxide in the solution:

ν=m/M=15/40=0.375 mol.

Mass of solvent (water) in kilograms:

85 grams of H 2 O \u003d 85/1000 \u003d 0.085 kg of H 2 O in this solution.

After that, the molar concentration is determined:

Cm=(ν/m)=0.375/0.085=4.41 mol/kg.

In accordance with these typical tasks you can solve most of the others on the definition of molality and molarity.

#3 Technologist OP

C g/l = M*1.2050*10 -1.5

where M is the molar mass in grams of the solute

#4 aversun

Isn't M the molar mass? Oo

#5 Technologist OP

What did I write about? is the molar mass (in grams) of the solute

#6 aversun

#7 Technologist OP

Number of users reading this topic: 0

0 users, 0 guests, 0 hidden users

Convert from grams to moles and from moles to grams

The calculator converts from the mass of a substance given in grams to the amount of a substance in moles and vice versa.

For tasks in chemistry, it may be necessary to convert the mass of a substance in grams to the amount of a substance in moles and vice versa.

This is solved through a simple ratio:

Mass of a substance in grams

Amount of substance in moles

Molar mass of a substance in grams/mol

And, in fact, the most difficult moment here is the definition of molar mass chemical compound.

Molar mass is a characteristic of a substance, the ratio of the mass of a substance to the number of moles of this substance, that is, the mass of one mole of a substance. For individual chemical elements, the molar mass is the mass of one mole of individual atoms of this element, that is, the mass of atoms of a substance taken in an amount equal to the Avogadro number (in fact, the Avogadro number is the number of carbon-12 atoms in 12 grams of carbon-12). Thus, the molar mass of an element, expressed in g / mol, numerically coincides with the molecular mass - the mass of an atom of an element, expressed in a. e.m. (atomic unit of mass). And the molar masses of complex molecules (chemical compounds) can be determined by summing up the molar masses of their constituent elements.

Fortunately, our site already has a Molar Mass of Compounds calculator that calculates the molar mass of chemical compounds based on the atomic mass data from the Periodic Table reference book. It is used to get the molar mass from the chemical compound formula entered in the calculator below.

The calculator below calculates the mass of a substance in grams or the amount of a substance in moles, depending on the choice of the user. For reference, the molar mass of the compound and the details of its calculation are also displayed.

Chemical elements should be written as they are written in the periodic table, i.e., take into account large and small letters. For example Co - cobalt, CO - carbon monoxide, carbon monoxide. So Na3PO4 is correct, na3po4, NA3PO4 is wrong.

Unit converter

Unit Converter Convert millimol per liter [mmol/l]<->mole per liter [mol/l]

How to improve mobile phone reception?

More about molar concentration

General information

The concentration of a solution can be measured in many ways, such as the ratio of the mass of the solute to the total volume of the solution. In this article, we will look at molar concentration, which is measured as the ratio between the amount of a substance in moles to the total volume of a solution. In our case, a substance is a soluble substance, and we measure the volume for the entire solution, even if other substances are dissolved in it. The amount of a substance is the number of elementary constituents, such as atoms or molecules of a substance. Since even a small amount of a substance usually contains a large number of elementary components, special units, moles, are used to measure the amount of a substance. One mole is equal to the number of atoms in 12 g of carbon-12, which is approximately 6×10²³ atoms.

It is convenient to use moths if we are working with an amount of a substance so small that its amount can be easily measured with home or industrial devices. Otherwise, one would have to work with very large numbers, which is inconvenient, or with very small weights or volumes, which are difficult to find without specialized laboratory equipment. Atoms are most often used when working with moles, although other particles, such as molecules or electrons, can also be used. It should be remembered that if not atoms are used, then this must be indicated. Sometimes molar concentration is also called molarity.

Molarity should not be confused with molality. Unlike molarity, molality is the ratio of the amount of solute to the mass of the solvent, and not to the mass of the entire solution. When the solvent is water and the amount of solute is small compared to the amount of water, then molarity and molality are similar in meaning, but otherwise they usually differ.

Factors affecting molar concentration

Units

How to find molar concentration

Examples

Since the oxygen in the formula is O₃, it is necessary to multiply the atomic mass of oxygen by 3. We get 47.9982. Now add the masses of all atoms and get 84.006609. The atomic mass is indicated in the periodic table in atomic mass units, or a. e. m. Our calculations are also in these units. One a. e.m. is equal to the mass of one mole of a substance in grams. That is, in our example, the mass of one mole of NaHCO₃ is 84 grams. In our task - 51 grams of soda. We find the molar mass by dividing 51 grams by the mass of one mole, that is, by 84 grams, and we get 0.6 moles.

It turns out that our solution is 0.6 moles of soda dissolved in 20 liters of water. We divide this amount of soda by the total volume of the solution, that is, 0.6 mol / 20 l \u003d 0.03 mol / l. Since a large amount of solvent and a small amount of solute were used in the solution, its concentration is low.

Let's consider another example. Find the molar concentration of one sugar cube in a cup of tea. Table sugar is made up of sucrose. First, let's find the weight of one mole of sucrose, the formula of which is C₁₂H₂₂O₁₁. Using the periodic table, we find the atomic masses and determine the mass of one mole of sucrose: 12 × 12 + 22 × 1 + 11 × 16 = 342 grams. There are 4 grams of sugar in one cube of sugar, which gives us 4/342 = 0.01 moles. There are about 237 milliliters of tea in one cup, so the concentration of sugar in one cup of tea is 0.01 moles / 237 milliliters × 1000 (to convert milliliters to liters) = 0.049 moles per liter.

Application

Molar concentration is widely used in calculations related to chemical reactions. The branch of chemistry that calculates the ratios between substances in chemical reactions and often works with moles is called stoichiometry. The molar concentration can be found from the chemical formula of the final product, which then becomes a soluble substance, as in the soda solution example, but you can also first find this substance from the formulas of the chemical reaction during which it is formed. To do this, you need to know the formulas of the substances involved in this chemical reaction. Having solved the chemical reaction equation, we find out the formula of the molecule of the solute, and then we find the mass of the molecule and the molar concentration using the periodic table, as in the examples above. Of course, it is possible to perform calculations in reverse order, using information about the molar concentration of a substance.

Let's consider a simple example. This time we mix baking soda with vinegar to see an interesting chemical reaction. Both vinegar and baking soda are easy to find - you probably have them in your kitchen. As mentioned above, the formula for baking soda is NaHCO₃. Vinegar is not a pure substance, but a 5% solution of acetic acid in water. The formula for acetic acid is CH₃COOH. The concentration of acetic acid in vinegar can be more or less than 5%, depending on the manufacturer and the country in which it is made, as the concentration of vinegar varies from country to country. In this experiment, you do not have to worry about the chemical reactions of water with other substances, since water does not react with soda. We only care about the volume of water when we later calculate the concentration of the solution.

First, we solve the equation for the chemical reaction between soda and acetic acid:

NaHCO₃ + CH₃COOH → NaC₂H₃O₂ + H₂CO₃

The reaction product is H₂CO₃, a substance that, due to low stability, enters into a chemical reaction again.

As a result of the reaction, we get water (H₂O), carbon dioxide (CO₂) and sodium acetate (NaC₂H₃O₂). We mix the resulting sodium acetate with water and find the molar concentration of this solution, just as before we found the concentration of sugar in tea and the concentration of soda in water. When calculating the volume of water, it is necessary to take into account the water in which acetic acid is dissolved. Sodium acetate is an interesting substance. It is used in chemical heating pads, such as hand warmers.

When using recipes, whether in cooking, in making medicines, or in creating the ideal environment for aquarium fish, it is necessary to know the concentration. In everyday life, it is most often convenient to use grams, but in pharmaceuticals and chemistry, molar concentration is more often used.

In pharmaceuticals

When creating drugs, the molar concentration is very important, since it determines how the drug affects the body. If the concentration is too high, then the drugs can even be fatal. On the other hand, if the concentration is too low, then the drug is ineffective. In addition, concentration is important in the exchange of fluids across cell membranes in the body. When determining the concentration of a liquid that must either pass or, conversely, not pass through the membranes, either the molar concentration is used, or the osmotic concentration is found with its help. Osmotic concentration is used more often than molar concentration. If the concentration of a substance, such as a drug, is higher on one side of the membrane than on the other side of the membrane, such as inside the eye, then the more concentrated solution will move across the membrane to where the concentration is lower. This flow of solution across the membrane is often problematic. For example, if fluid moves into the interior of a cell, for example, into a blood cell, then it is possible that due to this overflow of fluid, the membrane will be damaged and rupture. Leakage of fluid from the cell is also problematic, as this will disrupt the performance of the cell. Any drug-induced flow of fluid through the membrane out of or into the cell is desirable to prevent, and to do this, the concentration of the drug is sought to be similar to that of a fluid in the body, such as blood.

It is worth noting that in some cases the molar and osmotic concentrations are equal, but this is not always the case. It depends on whether the substance dissolved in water has broken down into ions in the process of electrolytic dissociation. When calculating the osmotic concentration, particles in general are taken into account, while when calculating the molar concentration, only certain particles, such as molecules, are taken into account. Therefore, if, for example, we are working with molecules, but the substance has decomposed into ions, then there will be less molecules than the total number of particles (including both molecules and ions), and hence the molar concentration will be lower than the osmotic one. To convert the molar concentration to osmotic concentration, you need to know the physical properties of the solution.

In the manufacture of drugs, pharmacists also take into account the tonicity of the solution. Tonicity is a property of a solution that depends on concentration. Unlike osmotic concentration, tonicity is the concentration of substances that the membrane does not let through. The process of osmosis causes solutions with a higher concentration to move into solutions with a lower concentration, but if the membrane prevents this movement by not passing the solution through, then there is pressure on the membrane. Such pressure is usually problematic. If a drug is intended to enter the blood or other body fluid, then the tonicity of the drug must be balanced against the tonicity of the body fluid to avoid osmotic pressure on the membranes in the body.

To balance tonicity, drugs are often dissolved in an isotonic solution. An isotonic solution is a solution of table salt (NaCL) in water at a concentration that balances the tonicity of the fluid in the body and the tonicity of the mixture of this solution and the drug. Usually isotonic solution is stored in sterile containers and infused intravenously. Sometimes it is used in its pure form, and sometimes - as a mixture with medicine.

You may also be interested in other converters from the group "Hydraulics and hydromechanics - fluids":

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

Hydraulics and Hydromechanics - Fluids

Molar concentration

The molar concentration of a solution is a value that characterizes the quantitative composition of the solution and is numerically equal to the number of moles of the solute in one liter of the solution. In the International System of Units (SI) it is measured in mol/m³.

A mole (denoted by a mole) is a unit of measure for the amount of a substance. Corresponds to the amount of a substance that contains 6.(27)×10²³ particles (molecules, atoms, ions, or any other identical structural particles). 6.(27)×10²³ is Avogadro's constant, equal to the number of atoms in 12 grams of pure carbon-12 (¹²C). Thus, the number of atoms in one mole of any substance is constant and equal to Avogadro's number N A . In other words, a mole is the amount of a substance whose mass, expressed in grams, is numerically equal to its mass in atomic mass units.

Using the Molar Concentration Converter

These pages contain unit converters that allow you to quickly and accurately convert values from one unit to another, as well as from one system of units to another. Converters will be useful for engineers, translators and anyone who works with different units of measurement.

Use the converter to convert several hundred units in 76 categories, or several thousand pairs of units, including metric, imperial and US units. You can convert units of length, area, volume, acceleration, force, mass, flow, density, specific volume, power, pressure, voltage, temperature, time, moment, speed, viscosity, electromagnetic and others.

Note. Due to the limited accuracy of the conversion rounding errors may occur. In this converter, integers are considered accurate up to 15 digits, and the maximum number of digits after a decimal point or point is 10.

To represent very large and very small numbers, this calculator uses computer exponential notation, which is an alternative form of normalized exponential (scientific) notation, in which numbers are written in the form a · 10 x . For example: \u003d 1.103 10 6 \u003d 1.103E + 6. Here E (short for exponent) - means "10^", i.e. ". multiply by ten to the power. ». Computer exponential notation is widely used in scientific, mathematical and engineering calculations.

Select the unit to convert from from the left list of units.
Select the unit to convert to from the list of units on the right.
Enter a number (for example, "15") in the Initial Value field.
The result will immediately appear in the "Result" field and in the "Converted value" field.
You can also enter a number in the right field "Converted value" and read the result of the conversion in the fields "Initial value" and "Result".

We are working to ensure the accuracy of TranslatorsCafe.com's converters and calculators, however we cannot guarantee that they are free of errors or inaccuracies. All information is provided "as is" without warranty of any kind. Terms.

If you notice an inaccuracy in the calculations or an error in the text, or you need another converter for converting from one unit of measure to another, which is not on our website - write to us!

How to Calculate the Molarity of a Solution

Molarity describes the ratio between moles of a solute and the volume of a solution. For a detailed understanding of how to find the molarity of a solution when moles, liters, grams and/or milliliters are given, read on.

Steps Edit

Method 1 of 4:

Method One: Calculating Molarity Given Moles and Volume Edit

Method 2 of 4:

Method Two: Calculating Molarity Given Mass and Volume Edit

Method 3 of 4:

Method Three: Calculating Molarity Given Moles and Milliliters Edit

Method 4 of 4:

Additional practice challenge Edit

Additional articles

find the number of protons, neutrons and electrons

Education in the Volga region

First of all, it is necessary to clarify one very important feature of concentration in any of its expressions - concentration always has a dimension. Often, concentration is called something that in fact it is not. For example, an alcohol content of 5% by volume is not a concentration, it is a proportion. Percentages are not units. Dimension is always one thing divided by something else, for example: g / mol, mol / liter, etc.

Let us briefly consider the main ways of expressing concentration.

Molar concentration, or simply molarity. Unit mol/l. This concentration expression gives the number of moles of a solute in one liter of solution. Knowing the formula of a substance, mole / liter is easy to convert to grams / liter. For example, if the concentration of sodium hydroxide solution NaOH is 1 mol / l (1 M NaOH), then one liter of such a solution will contain 40 grams of sodium hydroxide (the molar mass of NaOH is 40 g / mol, calculated using the periodic table). However, these data do not allow us to calculate the mass fraction of sodium hydroxide in the solution - for this it is necessary to know the mass of the dissolved substance in 1 kg, and not in 1 liter of solution. To go from liters to kilograms, you need to know the density of our solution. For 1M NaOH it is 1.045 g/ml. Those. one liter of our solution weighs not 1000 g, but 1000 ml * 1.045 g / ml \u003d 1045 g. 40 g is 3.83% of 1045 g. When calculating the fraction (mass, volume, molar), the numerator and denominator of the fraction always coincide, therefore, the fraction itself is a dimensionless quantity. In no case can you calculate percentages by putting grams of a dissolved substance in the numerator, and liters of solution in the denominator. You must first convert liters to kilograms using the density of the solution, ρ.

Molar concentration differs from molar concentration, or molality. It shows the number of moles of solute per kilogram of solvent. Molar concentration is often used where it is necessary to calculate the concentration of a solution from the change in its freezing or boiling point compared to a pure solvent.

Units of measurement in clinical and biochemical diagnostics

In accordance with State standard, in all branches of science and technology, including medicine, the use of units of the International System of Units (SI) is mandatory.

The SI unit of volume is the cubic meter (m3). For convenience in medicine, it is allowed to use the volume unit liter (l; 1 l \u003d 0.001 m3).

A unit of quantity of a substance containing the same structural elements, how many atoms are contained in a 12C carbon nuclide with a mass of 0.012 kg, is a mole, that is, a mole is the amount of a substance in grams, the number of which is equal to the molecular weight of this substance.

The number of moles corresponds to the mass of a substance in grams divided by the relative molecular weight of the substance.

1 mol = 10^3 mmol = 10^6 µmol = 10^9 nmol = 10^12 pmol

Only for indicators whose molecular weight is unknown or cannot be measured because it lacks physical sense(total protein, total lipids, etc.), the mass concentration is used as a unit of measurement - grams per liter (g / l).

A very common unit of concentration in the recent past in clinical biochemistry was the milligram-percent (mg%) - the amount of a substance in milligrams contained in 100 ml of biological fluid. To convert this value to SI units, the following formula is used:

mmol / l \u003d mg% 10 / molecular weight of the substance

The previously used concentration unit equivalent per liter (eq/l) is to be replaced by the unit mole per liter (mol/l). To do this, the value of the concentration in equivalents per liter is divided by the valency of the element.

The activity of enzymes in SI units is expressed in the number of moles of the product (substrate) formed (transformed) in 1 s in 1 l of solution - mol / (s-l), µmol / (s-l), nmol / (s-l).

mmol per liter

The concentration of substances in solutions can be expressed in different ways. On this page you will get to know them. The most commonly used mass fraction of a solute, molar and normal concentration.

The mass fraction of the dissolved substance w(B) is a dimensionless quantity equal to the ratio of the mass of the dissolved substance to the total mass of the solution m:

The mass fraction of the dissolved substance w (B) is usually expressed in fractions of a unit or as a percentage. For example, the mass fraction of the dissolved substance - CaCl2 in water is 0.06 or 6%. This means that a solution of calcium chloride weighing 100 g contains calcium chloride weighing 6 g and water weighing 94 g.

How many grams of sodium sulfate and water are needed to prepare 300 g of a 5% solution?

m is the mass of the solution in g

m(H 2 O) \u003d 300 g - 15 g \u003d 285 g.

Thus, to prepare 300 g of a 5% sodium sulfate solution, you need to take 15 g of Na 2 SO 4) and 285 g of water.

The molar concentration C(B) shows how many moles of a solute are contained in 1 liter of solution.

where M(B) is the molar mass of the solute, g/mol.

Molar concentration is measured in mol/l and is denoted by "M". For example, 2 M NaOH is a 2 molar solution of sodium hydroxide. One liter of such a solution contains 2 mol of the substance or 80 g (M(NaOH) = 40 g/mol).

What mass of potassium chromate K2CrO4 should be taken to prepare 1.2 liters of 0.1 M solution?

Thus, to prepare 1.2 liters of a 0.1 M solution, you need to take 23.3 g of K 2 CrO 4 and dissolve in water, and bring the volume to 1.2 liters.

The concentration of a solution can be expressed as the number of moles of solute per 1000 g of solvent. This expression of concentration is called the molality of the solution.

The normality of a solution refers to the number of gram equivalents of a given substance in one liter of solution or the number of milligram equivalents in one milliliter of solution.

Gram - the equivalent of a substance is the number of grams of a substance, numerically equal to its equivalent. For complex substances- this is the amount of a substance that directly or indirectly corresponds to 1 gram of hydrogen or 8 grams of oxygen during chemical transformations.

E base \u003d M base / number of hydroxyl groups replaced in the reaction

E acid \u003d M acid / number of hydrogen atoms replaced in the reaction

E salt \u003d M salt / product of the number of cations and its charge

Calculate the gram equivalent (g-equiv.) of sulfuric acid, calcium hydroxide, and aluminum sulfate.

Normality values are denoted by the letter "H". For example, a decinormal solution of sulfuric acid is designated "0.1 N solution of H 2 SO 4 ". Since normality can only be determined for a given reaction, the value of normality of the same solution may not be the same in different reactions. Thus, a one-molar solution of H 2 SO 4 will be one-normal when it is intended to react with an alkali to form NaHSO 4 hydrosulfate, and two-normal in the reaction to form Na 2 SO 4 .

Calculate the molarity and normality of a 70% H 2 SO 4 solution (r = 1.615 g/ml).

To calculate molarity and normality, you need to know the number of grams of H 2 SO 4 in 1 liter of solution. A 70% H2SO4 solution contains 70 g of H2SO4 per 100 g of solution. This weight of solution occupies a volume

V = 100 / 1.615 = 61.92 ml

Therefore, 1 liter of solution contains 70 1000 / 61.92 = 1130.49 g H 2 SO 4

Hence the molarity of this solution is: 1130.49 / M (H 2 SO 4) \u003d 1130.49 / 98 \u003d 11.53 M

The normality of this solution (assuming that the acid is used in the reaction as a dibasic one) is 1130.49 / 49 = 23.06 H

When converting a percentage concentration to a molar one and vice versa, it must be remembered that the percentage concentration is calculated for a certain mass of the solution, and the molar and normal concentrations are calculated for the volume, therefore, for conversion, it is necessary to know the density of the solution. If we denote: c - percentage concentration; M is the molar concentration; N - normal concentration; e - equivalent mass, r - density of the solution; m is the molar mass, then the formulas for converting from percentage concentration will be as follows:

The same formulas can be used if you need to convert the normal or molar concentration to a percentage.

What is the molar and normal concentration of a 12% sulfuric acid solution, the density of which is p = 1.08 g/cm3?

The molar mass of sulfuric acid is 98. Therefore,

Substituting the necessary values into the formulas, we get:

a) The molar concentration of a 12% sulfuric acid solution is

b) The normal concentration of a 12% sulfuric acid solution is

Sometimes in laboratory practice it is necessary to recalculate the molar concentration to normal and vice versa. If the equivalent mass of a substance is equal to the molar mass (For example, for HCl, KCl, KOH), then the normal concentration is equal to the molar concentration. So, 1 n. solution of hydrochloric acid will be simultaneously 1 M solution. However, for most compounds, the equivalent mass is not equal to the molar and, therefore, the normal concentration of solutions of these substances is not equal to the molar concentration.

To convert from one concentration to another, you can use the formulas:

Normal concentration of 1 M sulfuric acid solution

Molar concentration 0.5 N. Na2CO3

Evaporation, dilution, concentration, mixing solutions

There is mg of the initial solution with a mass fraction of the dissolved substance w 1 and a density ρ 1 .

As a result of evaporation of the initial solution, its mass decreased by D m g. Determine the mass fraction of the solution after evaporation w 2

Based on the definition of the mass fraction, we obtain expressions for w 1 and w 2 (w 2 > w 1):

(where m1 is the mass of the solute in the initial solution)

Evaporated 60 g of a 5% copper sulfate solution to 50 g. Determine the mass fraction of salt in the resulting solution.

m = 60 g; Dm \u003d 60 - 50 \u003d 10 g; w 1 \u003d 5% (or 0.05)

What mass of the substance (X g) must be additionally dissolved in the initial solution in order to prepare a solution with a mass fraction of the dissolved substance w 2 ?

Based on the definition of the mass fraction, we will compose an expression for w 1 and w 2:

(where m1 is the mass of the substance in the initial solution).

Solving the resulting equation for x, we get:

How many grams of potassium chloride must be dissolved in 90 g of an 8% solution of this salt so that the resulting solution becomes 10%?

We mixed m1 grams of solution No. 1 with a mass fraction of substance w 1 and m 2 grams of solution No. 2 with a mass fraction of substance w 2. A solution (No. 3) was formed with a mass fraction of the dissolved substance w 3 . How do the masses of the initial solutions relate to each other?

Let w 1 > w 2, then w 1 > w 3 > w 2. The mass of the dissolved substance in solution No. 1 is w1 · m1, in solution No. 2 - w 2 · m 2 . The mass of the resulting solution (No. 3) - (m 1 - m 2). The sum of the masses of the solute in solutions No. 1 and No. 2 is equal to the mass of this substance in the resulting solution (No. 3):

Thus, the masses of the mixed solutions m1 and m2 are inversely proportional to the differences in the mass fractions w1 and w2 of the mixed solutions and the mass fraction of the mixture w3. (Rule of mixing).

For ease of use mixing rules apply rule of the cross :

m1 / m2 = (w3 - w2) / (w1 - w3)

To do this, subtract the smaller one diagonally from the larger concentration value, get (w 1 - w 3), w 1 > w 3 and (w 3 - w 2), w 3 > w 2. Then make up the mass ratio of the initial solutions m 1 / m 2 and calculate.

Determine the masses of the initial solutions with a mass fraction of sodium hydroxide of 5% and 40% if, when they are mixed, a solution of 210 g with a mass fraction of sodium hydroxide of 10% is formed.

Based on the definition of the mass fraction, we obtain expressions for the values of the mass fractions of the dissolved substance in the initial solution No. 1 (w 1) and the resulting solution No. 2 (w 2):

Solution No. 2 is obtained by diluting solution No. 1, therefore m 1 = m 2. The expression for m 2 should be substituted into the formula for V 1 . Then

m1(solution) / m2(solution) = w2 / w1

With the same amount of solute, the masses of solutions and their mass fractions are inversely proportional to each other.

Determine the mass of a 3% hydrogen peroxide solution, which can be obtained by diluting 50 g of its 3% solution with water.

molar concentration. What does molar and molal concentration mean? Education in the Volga region

More about molar concentration

General information

Factors affecting molar concentration

Units

How to find molar concentration

Examples

Application

In pharmaceuticals

1.3.4. The relationship between the mass of a substance and its quantity

1.3.5. The relationship between the volume of a substance and its quantity

General information about solutions and solubility

Concentration and ways of expressing it

Molar concentration

Molar concentration

Additional formulas required for calculations

Examples of tasks for molarity and molality. Task #1

Task #2

Task #3

Task #4

Task #5

#3 Technologist OP

#4 aversun

#5 Technologist OP

#6 aversun

#7 Technologist OP

Number of users reading this topic: 0

Convert from grams to moles and from moles to grams

Unit converter

Unit Converter Convert millimol per liter [mmol/l]<->mole per liter [mol/l]

How to improve mobile phone reception?

More about molar concentration

General information

Factors affecting molar concentration

Units

How to find molar concentration

Examples

Application

In pharmaceuticals

You may also be interested in other converters from the group "Hydraulics and hydromechanics - fluids":

Hydraulics and Hydromechanics - Fluids

Molar concentration

Using the Molar Concentration Converter

How to Calculate the Molarity of a Solution

Steps Edit

Method 1 of 4:

Method 2 of 4:

Method 3 of 4:

Method 4 of 4:

Additional articles

Education in the Volga region

Units of measurement in clinical and biochemical diagnostics

mmol per liter

Read also:

Amount of movement Amount of movement of a system of material points

Eccentric tension - compression

Examples Determine if a sequence is infinitesimal

new entries