t's not molecular weight, but for a colloid solution, the distribution of this property is commonly assayed using dynamic light scattering. It's not the activity coefficient, but in the Debye-Huckel equation, the variable "a" encodes this quantity, and this parameter notably does not appear in the Davies equation. A method of chromatography that is used to separate molecules by this property commonly uses a Sephacryl resin and is either referred to as gel- permeation chromatography or named for 
t's not molecular weight, but for a colloid solution, the distribution of this property is commonly assayed using dynamic light scattering. It's not the activity coefficient, but in the Debye-Huckel equation, the variable "a" encodes this quantity, and this parameter notably does not appear in the Davies equation. A method of chromatography that is used to separate molecules by this property commonly uses a Sephacryl resin and is either referred to as gel- permeation chromatography or named for the exclusion of this property. For an ideal gas, this quantity is usually assumed to be significantly smaller than the distance between the molecules or the space occupied by the container. For 10 points, name this quantity which is accounted for by the "b" term of the van Der Waals equation, which is how much space a molecule takes up.
t's not molecular weight, but for a colloid solution, the distribution of this property is commonly assayed using dynamic light scattering.