# Thermal physics -- Converting the internal energy of argon atoms to temperature

Kathhhriine
Homework Statement:
The internal energy of 6.46 grams of argon is 568 J. What is the temperature of the argon atoms?
Relevant Equations:
I tried using U=3/2 NKbT, but i dont seem to get the correct answer..
I tried using U=3/2 NKbT, but i don't seem to get the correct answer..

Homework Helper
Gold Member
Please show us what answer you got and how you got it. Without this information we are as much in the dark as you are.

Kathhhriine
Please show us what answer you got and how you got it. Without this information we are as much in the dark as you are.
I rearranged u=3/2NkbT, to get T=(2U)/(3NKb). Then i changed from mass to molecules, by taking N=(m/M)x(avogardos)=(6.46/39.9)x6.02x10^23=9.75x10^22. I plotted in the values; T=(2x568)/(9.75x10^22 x 1.3x10^-23 x3) =298K. The value given in the solution is 282K.

Homework Helper
Gold Member
I got 281.4 K. I think you have a round-off error. Use the more accurate value ##k_B=1.38\times10^{23}~\mathrm{J/K}## for the Boltzmann constant.

BTW, Welcome to PF!

With an atomic mass of 39.95 u for Argon I got 281.8 K which rounds off to your given answer.

• Binh Minh Duong, Kathhhriine and etotheipi
Kathhhriine
I got 281.4 K. I think you have a round-off error. Use the more accurate value ##k_B=1.38\times10^{23}~\mathrm{J/K}## for the Boltzmann constant.

BTW, Welcome to PF!

With an atomic mass of 39.95 u for Argon I got 281.8 K which rounds off to your given answer.
Thank you!