Question

What is the translational kinetic energy of a Helium molecule (He) at 1500 K?

• A. 2.189 eV
• B. 0.194 eV
• C. 1.215 eV
• D. 10.068 eV

Answer 1

The correct option is B

0.194 eV

Helium, at such high temperature, is a good example of a monoatomic ideal gas. All its internal energy will only be translational kinetic energy, related to the temperature as -

Internal energy = kinetic energy $=\frac{3}{2}{K}_{B}T.$

$=\frac{3}{2}\times 1.38\times {10}^{-23}\times 1500J$

$=3.1\times {10}^{-20}J$

$=(3.1\times {10}^{-20})\times (6.242\times {10}^{18})eV$

= 0.194 eV.