#$355.$ Gas Mixing with Temperature Differences

An insulated tank that contains $1$ kg of $O_2$ at $12C$ and $250$ kPa is connected to a $3m^3$ uninsulated tank that contains $N_2$ at $40C$ and $550$ kPa $.$ The valve connecting the two tanks is opened, and the two gases form a homogeneous mixture at $T_0=T_{\text{e}\text{n}\text{v}}=20C.$

Determine the final pressure in the tank.

$P_{\text{f}\text{i}\text{n}\text{a}\text{l}}$ : kPa