Temperature required for new rms speed

[rubenhero]

Homework Statement

c) Find T, the temperature at which He gas molecules have an rms speed of v = 733 m/s.

Homework Equations

V_rms = √(3kT/m)

The Attempt at a Solution

(V_rms²m)/3k = T
(733²*.004kg)/(3*1.381e-23J/k) = T
5.187e25k = T

Any help with figuring out what I did wrong is appreciated!

 

[grzz]

Is not 'm' the mass of one MOELECULE of hydrogen?

 

[mtayab1994]

You could use the following to solve if you are given the quantity of material (n):

P*V=n*R*T <=> T=(P*V)/(n*R)

For R is a constant: R=8.31

 

[rubenhero]

Thank you grzz and mtayab1994 for responding. It would be easier if the problem did provide n to use PV = nRT. I am confused, should I be using .008 kg for the mass because helium gas has 2 atoms?

 

[mtayab1994]

Thank you grzz and mtayab1994 for responding. It would be easier if the problem did provide n to use PV = nRT. I am confused, should I be using .008 kg for the mass because helium gas has 2 atoms?

no you are fine with using .004kg

 

[mtayab1994]

By the way you can use the following as well