Physical Chemistry Nonideal Solutions Activity and Activity Coefficients u-u=RTIn, - x;=RT In x The ratio is the measure of the departure from ideal behavior activity coefficient every solution (10.5) The activity coefficient yi measures the degree of departure of substance is behavior from ideal or ideally dilute e behavior The activity a; is obtained from the mole fraction x by correcting for nonideality8 Activity and Activity Coefficients Nonideal Solutions         − = − = i i i i i d i i x a   RT ln a RT ln x RT ln The ratio is the measure of the departurefrom ideal behavior. i i x a i i i x a   ai =  i xi every solution (10.5)* activity coefficient The activity coefficient i measures the degree of departure of substance i’s behavior from ideal or ideally dilute behavior. The activity ai is obtained from the mole fraction xi by correcting for nonideality. Physical Chemistry