## What is the internal energy u of one mole of air on a very hot summer day (35∘c)? express your answer numerically in joules to two significa

Question

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## Answers ( 1 )

– For solving this problem, we have to take in account the degree of freedom of air molecules.

– As, molecules of air have five degrees of freedom (three translational and two rotational)

– For each molecule, the kinetic energy of each degree of freedom = 1/2 KT

– So, K.E of 1 molecule for 5 degrees of freedom = 5/2KT

So, for molecules of air K.E = 5/2 KT = 5/2 x 1 x 1.38 x 10u207bu00b2u00b3 x 308 = 1062.6 x 10u207bu00b2u00b3 J

1 mole of air contains 6.022 x 10u00b2u00b3 molecules

K.E. of 1 mole = 1062.6 x 10u207bu00b2u00b3 x 6.022 x 10u00b2u00b3 = 6400 J