Physics · University
Classical monatomic ideal-gas internal energy · formula reference
Only translational degrees of freedom contribute in this classical ideal-gas model.
Formula
Only translational degrees of freedom contribute in this classical ideal-gas model.
U = (3/2)nRT
Worked example
Using R=8.314 J/(mol·K), calculate the internal energy of 9 mol of a classical monatomic ideal gas at 630 K. Round the final result to 4 decimal places if needed. Answer in J.
Three quadratic translational terms contribute RT/2 each per mole. Therefore U=(3/2)(9)R(630).
70710.57 J
Prerequisites and checking
Algebra, calculus and the stated physical model. Keep units and rounding consistent. State the model conditions before applying the formula.
Further reading and review references
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