Molarity is expressed as

Molarity of expressed in

If N_(1),N_(2),N_(3),…… are the number of molcules with molecular masses M_(1),M_(2),(M_(3),… respectively ,then mass average molar mass is expressed as:

If N_(1),N_(2),N_(3),…… are the number of molcules with molecular masses M_(1),M_(2),(M_(3),… respectively ,then mass average molar mass is expressed as:

If N_1, N_2, N_3 , ..... are the number of molecules with molecular masses M_1,M_2,M_3 , .... respectively, then mass average molar mass is expressed as:

Why molality is preferred over molarity in expressing the concentration of solution ?