How to find the mass of matter?

In chemistry can not do without a lot of substances. After all, this is one of the most important parameters of a chemical element. We will tell you how to find the mass of matter in various ways in this article.

First of all, you need to find the right oneelement, using the periodic table, which you can download online or buy. Fractional numbers under the element sign are its atomic mass. It must be multiplied by the index. The index shows how many molecules of the element are contained in a given substance.

When you have a complex substance, you needmultiply the atomic mass of each element of matter by its index. Now it is necessary to add the atomic masses received by you. Such a mass is measured in units of gram / mol (g / mol). How to find the molar mass of a substance, we show on the example of calculating the molecular weight of sulfuric acid and water:
H2SO4 = (H) * 2 + (S) + (O) * 4 = 1 * 2 + 32 + 16 * 4 = 98 g / mol;

H2O = (H) * 2 + (O) = 1 * 2 + 16 = 18 g / mol.

The molar mass of simple substances, which consist of a single element, is calculated in the same way.
You can calculate the molecular weight according to the existing molecular weight table, which can be downloaded on the Internet or purchased from the bookstore
You can calculate the molar mass using formulas and equate it to the molecular mass. The units of measurement must be changed from "g / mole" to "amu".
When, for example, you know the volume, pressure,mass and temperature on the Kelvin scale (if Celsius, then it is necessary to translate), then you can find out how to find the molecular mass of a substance using the Mendeleev-Klaiperon equation:

M = (m * R * T) / (P * V),

where R is the universal gas constant; M is the molecular (molar mass), amu.
The molar mass can be calculated using the formula:
M = m / n,

where n is the amount of the substance; m is the mass of the substance. Here it is necessary to express the amount of matter by volume (n = V / VM) or Avogadro's number (n = N / NA).
If the value of the gas volume is given, then find itthe molecular mass can be taken by sealed balloon with a known volume and evacuating the air. Now you need to weigh the balloon on the scales. Next, pour gas into it and weigh again. The difference between the masses of an empty cylinder and a gas cylinder is the mass of the gas we need.
When you need to carry out the process of cryoscopy, you need to calculate the molecular weight by the formula:
M = P1 * Ek * (1000 / P2 * Δtk),

where P1 is the mass of the solute, g; P2is the mass of the solvent, g; Ek is a cryoscopic solvent constant, which can be determined from the corresponding table. This constant is different for different liquids; Δtk is the temperature difference, which is measured with a thermometer.