# Problem: A scientist measures the speed of sound in a monatomic gas to be 449 m/s at 20°C.What is the molar mass of this gas?

###### FREE Expert Solution

For an ideal gas, speed of sound is given as:

$\overline{){\mathbf{v}}{\mathbf{=}}\sqrt{\frac{\mathbf{\gamma }\mathbf{R}\mathbf{T}}{\mathbf{M}}}}$

Solve for M:

$\mathbit{M}\mathbf{=}\frac{\mathbf{\gamma }\mathbf{R}\mathbf{T}}{{\mathbf{v}}^{\mathbf{2}}}$

###### Problem Details

A scientist measures the speed of sound in a monatomic gas to be 449 m/s at 20°C.

What is the molar mass of this gas?