The ion activity product is the product of the concentration of ions and their activity. The concentration is the ratio of number of ions to volume of urine. - The lower the number of ions or larger volume of urine, the lower the concentration. The lower the concentration – the lower the IAP and thus lower RSS. - The higher the number of ions or lower volume of urine, the higher the the concentration – the higher the IAP and thus higher RSS. The activity is how strongly the ions interact with other things in their environment. - Higher valency ions (divalent and trivalent) had a lower activity. They are larger and cannot move around solution as much to form bonds. This lowers the IAP and thus the RSS. - The stronger bonds they form, the lower activity they have. This lowers IAP and thus the RSS. using an analogy of the ions being lemons and sugar and the volume of urine being a small and large pitcher, and the strength being larger lemons and sugar and increased number of lemons and sugar See more