2.1.5 Stoichiometric equation and the extent of a reaction stoichiometric equation: aA+bB→yY+zZ→0=-aA-bB+yY+zZ 0=∑sB B B-stoichiometric number of substance B VA=-a,VB=-b,Vy=y,V7=Z extent of reaction(S,Zeta发音)：反应进展的程度 5= △ng_n(5)-nB(O) the unit ofξis mol VB VB 2.1.5 Stoichiometric equation and the extent of a reaction  B— stoichiometric number of substance B stoichiometric equation： νA= -a， νB= -b， νY= y， νZ= z B B B B B ( ) (0)     n n − n =  = extent of reaction (ξ, Zeta发音)：反应进展的程度 the unit of ξ is mol = + → + B 0 B B A B Y Z  a b y z 0 = −aA − bB + yY + zZ