 # Sound velocity definition and calculation for an ideal gas

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1. Definition of the sound velocity
2. How to calculate the sound velocity
3. References of speed of sound in air
4. Excel calculation tool for sound velocity

## 1. Definition of the sound velocity in an ideal gas

The sound velocity, sometimes also called the speed of sound, is the distance traveled by a sound wave in a gas during a unit of time. It is generally expressed in m/s and is used in many process engineering calculations.

## 2. How to calculate the sound velocity for an ideal gas

The following formula can be used to calculate the speed of sound in an ideal gas : With :

a = speed of sound in m/s
k = specific heat ratio or isentropic coefficient
R = perfect gas constant = 8314
T = gas temperature in K
M = molecular weight in g/mol

## 3. References of speed of sound for common fluids

 Gas Speed of sound in m/s Air 20c 343 m/s Air 100c 386 m/s Air 150c 410 m/s

## 4. Excel Calculation Tool

The following Excel calculation tool will allow you to calculate the sound velocity for ideal gas : link to Excel calculation tool