# At 35°C, argon has a velocity of 300 m/s. What is the velocity of helium at the same temperature?

Jun 11, 2018

$\text{948 m/s}$

#### Explanation:

Velocity of gas molecules at constant temperature is inversely proportional to square root of Molar mass of gas

$\text{v" ∝ 1/sqrt"M}$

From above

"v"_"He"/"v"_"Ar" = sqrt("M"_"Ar"/"M"_"He")

"v"_"He" = "v"_"Ar" × sqrt("M"_"Ar"/"M"_"He")

$\textcolor{w h i t e}{\text{v"_"He") = "300. m/s" × sqrt("39.948 g/mol"/"4.0026 g/mol}}$

color(white)("v"_"He") = 947._8 "m/s"