87.4 Activity and activity coefficient 1. Concepts MX二vM+X m =v m mn三vm m+=m+mm,=(v+v)m mean ionic molality ri=r+r-n=(r+r) mean ionic activity coefficient a=(ata mean ionic activity y Mean ionic molality can be expressed in term of the molality of the solution, mean ionic activity coefficient can be measured experimentally, and then mean ionic activity can be determinedm+ = v+ m m− = v− m m v v v m v v 1 ( ) + −  = + − v v v 1 ( ) + −  = + −    mean ionic molality mean ionic activity coefficient  + −   = =  + − a a a m  v v v 1 ( ) mean ionic activity Mean ionic molality can be expressed in term of the molality of the solution, mean ionic activity coefficient can be measured experimentally, and then mean ionic activity can be determined. v a = a 1. Concepts §7.4 Activity and activity coefficient + −  = + − v v v m m m + −  = + − v v v   