Velocidade Média Molecular
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
v_rms = √(3kT/m)
About this calculator
The molecular average speed calculator determines the root mean square velocity (v_rms) of molecules in an ideal gas. The calculation uses the formula v_rms = √(3kT/m), where k is Boltzmann's constant, T is temperature in Kelvin, and m is the molecular mass in kilograms. This velocity represents a typical measure of molecular motion due to thermal agitation.
How it works: simply enter the gas temperature and the mass of a molecule. The calculator applies the formula and returns the average molecular speed. It is useful in physics and chemistry for understanding gas properties such as diffusion and thermal conductivity. For example, you can compare speeds of different gases at the same temperature.
When to use? In kinetic theory studies, engineering projects involving gases, or for educational purposes. Cautions: the formula assumes an ideal gas with no intermolecular interactions. Also, mass must be in kg (use molar mass divided by Avogadro's number). Temperature must be in Kelvin.
Frequently asked questions
What does v_rms mean?
v_rms is the root mean square velocity, a measure of the typical speed of molecules in a gas.
Can I use the calculator for liquids or solids?
No, the formula is only valid for ideal gases, where molecules do not interact.
What unit should I use for mass?
Mass must be in kilograms (kg). If you have the molar mass, divide by Avogadro's number (6.022 × 10^23) to get the mass of one molecule.
What if I use temperature in Celsius?
The formula requires temperature in Kelvin. Convert Celsius to Kelvin by adding 273.15.
Is the calculated speed the actual speed of molecules?
No, v_rms is a statistical average. Individual molecules have speeds distributed around this value.