Question

A sample of an ideal gas escapes into an evacuated container, there is
no change in the kinetic energy of the gas. Why?

Answer 1

There really isn't a "force of suction", that is an illusion. The only "force" that is mistaken as suction is a pressure based force from the higher pressure gas. 

And all that really is, is billiard ball-like collisions of the gas molecules, and some just drifting on their own history of collisions in the direction of the empty container. 

It is all elastic collisions between gas molecules and between container walls. No energy is dissipated. It all conserved as kinetic energy.