Molar volume refers to the amount of a unit substancematerialOfvolumeThat's the volume of one mole of material.One mole of any substance contains 6.02 × 10 structural particlestwenty-three。The mass of 1 mole of material is calledMolar mass。If the mass of an atom of 1 mole is expressed in grams, it is numerically equal to its atomic weight (equivalent to the gram atomic weight in the old unit);For a molecule of 1 mole, if its mass is expressed in grams, its numerical value is equal to its molecular weight (equivalent to the molecular weight of grams in the old unit).[1]
Ideally, one mole of gas isStandard atmospheric pressureThe volume under is 22.4L, and the more accurate is: Vm=22.41410L/mol。
Attention shall be paid to:
① It must be a standard condition (101kpa, 0 ℃).
② "Any gas" includesPure substanceIt also includes gas mixture.
③ 22.4 liters is an approximate value.
④ The unit is liter/mole (L/mol), not liter (L).
The volume of gas per unit mass is called the molar volume of gas. The gas with the same molar volume of gas containsNumber of particlesSame.The molar volume of gas is not fixed, it depends on the temperature andpressureIf at 25 ° 101KilopascalThe molar volume of the gas is 24.5 liters/mole. Under the same external conditions, the molar volume of the gas is the same.
1. At the same temperature and pressure, if V is the same, then N is the same, and n is the same.
2. At the same temperature and pressure, Vone/Vtwo=none/ntwo=None/N2。
3、P·V=n·R·T。
Molar mass and gram equivalent
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If a substance is composed of atoms, the molar mass of this substance is 6.022 × 10 atoms, which is numerically equivalent to the atomic weight of this element, in grams per mole (equivalent to the concept of gram atomic weight. Both the concepts of molar mass and gram atomic weight are used in this book).
If a substance is composed of molecules, the molar mass of the substance is 6.022 × 10 μ m, which is numerically equal to the molecular weight of the substance in grams per mole (equivalent to the concept of molecular weight in grams. The concepts of molecular weight and molecular weight in grams are used in this book).
For example:
The mass of 1 mole of Fe is 55.85g, i.e. 55.85g/mole.
1 mole HtwoThe mass of O is 18 g, that is, 18 g/mole.
1 mole HtwoSOfourThe mass of is 98 g, that is, 98 g/mole.
Therefore, the number of moles contained in a certain amount of substance can be calculated with the following formula:
Mole number=mass of substance (g)
Molar mass of the substance (g/mol)
Or, the mass of the substance (g)=number of moles × molar mass (g/mole).
The number of moles can be an integer or not.
The equivalent of a substance, expressed in grams, is called the gram equivalent of the substance.The relationship between the mass of the substance, the gram equivalent and the gram equivalent number is as follows:
Gram equivalent number of substance=mass of substance (g)
