分压定律 P111 ∑2=∑xp=p p n PTY PTV ( RTVPTV 分压力pV=R7分压定律 p T V p T V p T V p T V 分压力pi pV nR T = M pV n R T i i M = i i i p n x p n = = p x p i i =   p x p p i i = =