What is the Vrms, in m/s, for helium atoms at 4.8 K?

[Ashley Cornwell]

Homework Statement

What is the Vrms, in meters per second, for helium atoms at 4.8 K? (which is close to the point of liquefaction)

Homework Equations

Vrms= √(3RT)/(M)

The Attempt at a Solution

R=3.145
T= I think its 4.15 Kelvin? based on the point of liquefaction of helium being -269°C
-unsure about the temperature
M= I think its 0.004003 Kg based on the molar mass of helium

Vrms= Sqrt (3*3.1845*4.15)/(0.004003)

Any help would be greatly appreciated, I've tried this a million ways and can't seem to figure it out,
Thank You!

 

[TSny]

Welcome to PF!

You don't have the correct value of R if you are using SI units.

They want you to use 4.8 K for T.

Otherwise, your method looks correct.

 

[Ashley Cornwell]

Welcome to PF!

You don't have the correct value of R if you are using SI units.

They want you to use 4.8 K for T.

Otherwise, your method looks correct.

Thank You!