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It is known that atoms are small particles, and difficult to deal with them through normal measurements, so it was thought to deal with a sample or a large number of atoms, and in order to calculate the quantities of atoms, scientists found the number Avogadro, or Avogadro constant, The number of atoms in 12 grams of carbon 12C, the number of particles in a single mole of matter, and the number of avogadro 6.022 * 1023. The mole is the amount of matter containing a number of minutes, atoms or particles equal to the number of carbon atoms in 12 Carbon of carbon.
The carbon atom is chosen as a measure, because carbon atoms are the most abundant atoms in nature, and its mass can be measured accurately. Because the weight of one mole of carbon is known to be 12,000, scientists count the number of atoms in it. , The number of Avogadro.
Example 1: Calculate the number of carbon atoms in 122 grams of carbon, if you know that the mass of one atom of carbon equals 1.96629 * 10-23? Solution: Number of carbon atoms = (12 / 1.96629 * 10-23) = 6.0210 * 1023 = Avogadro number.
Solution: Number of carbon atoms = (12 / 1.96629 * 10-23) = 6.0210 * 1023 = Avogadro number.
Atomic molar mass, the mass of the atoms of the element, and its unit M-1, for example:
Atomic mass of carbon = 12 mol - 1
Atomic mass of hydrogen = 1 mol -1
Molecular mass of chlorine = 35.5 mol -1
Molecular molar mass, total molar mass forming a molecular compound, for example:
Molecular mass of water (H2O) = 2 * Molecular mass of hydrogen + Molecular mass of oxygen = 18 gm-1. Molecular Molecular Cluster H2SO4 = 22 * Molecular mass of hydrogen + Molecular mass of sulfur + 4 * Molecular mass of oxygen = 98 gm-1.
Example (3): Calculate the mass at 9.45 mM of N2O3?
Molar mass (N2O3) = 2 * 14 + 3 * 16 = 76 gm-1
Number of moles = mass / mass molar, 9.45 = mass / 76, if mass = 9.455 * 76 = 718.2 grams.
Number of Malls = (Mass / Mass)
Quantity of material = (number of moles / number of particles)
Example (2): Calculate the amount of material in a piece of copper with a mass of 922 grams.
Solution: Material quantity = (8.76 * 1023 / 6.02 * 1023) = 1.455 m.
Avogadro's law concluded a year 1811, a gas law, where the world created Avogad A relationship between the volume and quantity of gas under certain conditions, and concluded the following: (The equal volumes of different gases contain the same number of molecules provided that these sizes are measured under the same conditions of pressure and temperature) that is if we have a liter of helium, The same conditions of pressure and temperature, they will contain the same number of molecules.
Gas volume = constant * The amount of material for the gas, so that the volume Gas at ideal temperature and pressure = 22.4 liters.
Example (4): Calculate the volume in liters of 0.2022 mol of a gas under standard conditions. Solution: 1 mol = 22.4 liters, 0.202 mol =? If the size = 22.4 * 0.202 = 4.522 liters.
Example (5): How many oxygen gas particles are in 3,366 liters of oxygen gas under standard conditions of pressure and heat? Number of Oxygen Malls = (3.36 * 1) / 22.4 = 0.155 m.
Number of molecules = number of particles / number of avogadro, if the number of particles = 0.155 * 6.02 * 1023 = 9 * 1022 molecule.
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