1. The problem statement, all variables and given/known data The internal energy of a monoatomic ideal gas such as neon is simply the total kinetic energy of all its atoms. What is the internal energy of 2 liters of neon at a temperature of 200 K and pressure of 0.7 atm? 2. Relevant equations PV = nRT KE(ave) = 3/2kT U = 3/2nRT 3. The attempt at a solution KE = 1/2mv^2 From a previous problem, I figured out that v(rms) = 499.227 m/s. And, 2 liters of neon X 0.9002 g/L (density of neon) = 0.0018004 kg KE = 1/2(0.0018004 kg)(499.227 m/s) = 224.3546833 J (wrong answer) I feel like I am approaching this problem in the wrong manner. Please help!