Please help. Don't understand how to get to the correct answer of -9.11.

Question 11 10/10 pts N For a certain substance, it is known that when T = 634 Kand P = 3.3 bar, V = 452 cm/mol, a v = 1.8 x 10-31 K T = 4.6 x 10-5 bar 1, and Cp = 52 J'mol 1.K-1. What is the value for the Joule-Thomson coefficient for a valve with 6.5 kg/s flowing through it? ered 7.25 swer -9,911 margin of error +/- 1.5%