Nitrogen (n2) initially at 40°f and 14.7 lbf/in.2 fills a closed, rigid, 6.5-ft3 tank fitted with a paddle wheel. during a process, the paddle wheel provides 5 btu of energy transfer by work to the gas. the gas temperature reaches 80°f at the end of the process. assuming ideal gas behavior, determine the mass of nitrogen, in lb, and the heat transfer, in btu. kinetic and potential energy effects can be ignored.