Question

1) The internal energy function for a Van der Waals gas with constant cy is UCT, v) = n( cv1-3) where v=Vin is the specific volume. a) Find the change in temperature T-To that occurs in a free expansion when the volume changes from V, to 2V. The initial specific volume is v=25L/mol, the specific heat is Cy=2.5R and the parameter a is a=1.346 atm L-/mol (realistic value for N2 gas, note: latm=1.013 x 10 Pa). VOTO 2V, gas Perfect insulation Perfect insulation b) Write down the internal energy function if a corresponding experiment with a gas of constant Cy yields Tf-To=0? How can this experimental situation be approached?

Answer 1

In free expansion, the internal energy change is zero. su= 0. of U, - U2 = 0. n[CT-a] - [ CVT2 - 97 => C ( T-T ) - Q att ta an [ 2 an OJ an V. - Tf - To = -an Wocu - - a EUR (2.5) - 1.346x 1.013 410 x 10-6 2 x 125 x/03) x 8.3.14X2.5 = -0.13°c.