Calculator
Example Data Table
| Gas | Molar Mass (g/mol) | Temperature (K) | Average Molecular Speed (m/s) |
|---|---|---|---|
| Hydrogen | 2.016 | 300 | 1775.02 |
| Helium | 4.0026 | 300 | 1259.73 |
| Nitrogen | 28.0134 | 300 | 476.17 |
| Oxygen | 31.998 | 300 | 445.54 |
| Carbon Dioxide | 44.01 | 300 | 379.90 |
Formula Used
Average molecular speed: v = √(8RT / πM)
Most probable speed: vmp = √(2RT / M)
Root mean square speed: vrms = √(3RT / M)
Here, v is speed in meters per second, R is the gas constant, T is absolute temperature in Kelvin, and M is molar mass in kilograms per mole.
The calculator converts Celsius and Fahrenheit to Kelvin before solving. It also converts molar mass from grams per mole to kilograms per mole when needed.
As temperature rises, molecular speed rises. As molar mass rises, molecular speed falls. That is why light gases move faster than heavy gases at the same temperature.
How to Use This Calculator
- Enter a gas label for your reference.
- Type the gas temperature and select its unit.
- Type the molar mass and select the mass unit.
- Set decimal places and the graph temperature range.
- Press the calculate button to view results, graph, CSV, and PDF options.
FAQs
1) What is average molecular speed?
It is the mean speed of gas molecules predicted by Maxwell-Boltzmann statistics. It is not the same as the most probable speed or the root mean square speed.
2) Why is Kelvin used in the formula?
Gas speed equations require absolute temperature. Kelvin starts at absolute zero, so it keeps the thermodynamic relationship physically correct.
3) Can I enter Celsius or Fahrenheit?
Yes. The calculator converts Celsius or Fahrenheit to Kelvin before applying the speed equation.
4) Why must molar mass be in kg/mol?
The gas constant uses SI units. Converting molar mass to kilograms per mole keeps the result in meters per second.
5) Does pressure change the average molecular speed here?
Not directly in this ideal-gas speed formula. Temperature and molar mass control the computed average molecular speed.
6) Why do lighter gases move faster?
Molar mass is in the denominator under the square root. A smaller molar mass gives a larger speed at the same temperature.
7) Is average molecular speed the same as RMS speed?
No. RMS speed is always a bit larger than average speed for the same gas and temperature.
8) What does the Plotly graph show?
It shows how average molecular speed changes with temperature for the selected molar mass across your chosen Kelvin range.