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..

 

[kuruman]

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.

 

[kuruman]

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.

 

[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!