In tribute to **Avogadro**, also the number of particles (atoms, molecules, ions, or other particles) in** 1 mole** of a substance:

**6.022×10 ^{23}**

It was named after Avogadro as the **Avogadro constant** or** Avogadro number**. The Avogadro constant is one of the seven SI base units and is represented by *N*_{A}.

The **Avogadro’s Law **can be used for comparing the same substance under two different sets of conditions:

*V*_{1}* / n*_{1}* = V*_{2}* / n*_{2}

## Molar Volume of Gases

One of the most practical results of this law is the **molar volume of a gas**, **V _{m}**, which is about:

**V _{m} = 22.4 dm^{3} / mol**

It means, at standard temperature (273.15 K, 0°C) and standard atmospheric pressure (101.325 kPa), the molar volume is the same for all ideal gases. Note that it is under the ideal gas assumption. This value is strongly dependent on the pressure and the temperature. For example:

- for 273.15 K (0°C) and 100.00 kPa, the molar volume of an ideal gas is 22.71 dm
^{3}.mol^{−1} - for 298.15 K (25°C) and 100.00 kPa, the molar volume of an ideal gas is 24.79 dm
^{3}.mol^{−1}