PV = nRT. Assumptions: (1) Gas molecules are point particles (negligible volume). (2) No intermolecular forces. (3) Elastic collisions (KE conserved). (4) Random motion in all directions. (5) Average KE proportional to T. Kinetic energy: KE = $\frac{3}{2}$kT per molecule = $\frac{3}{2}$RT per mole (k = $\frac{R}{N_A}$ = Boltzmann constant = 1.38 x 10^-23 J/K). Pressure from kinetic theory: P = \frac{1}{3}$$\frac{mN}{V}$$u_{rms}^2 = $\frac{1}{3}$rho*$u_{rms}^2$. KE is independent of the nature of gas — depends only on temperature.