8.9.2 Precipitation of colloids by electrolytes Precipitating value: The lowest concentration of electrolyte( in mmol. dm)at which precipitation of colloid can be easily observed (precipitating efficiency/power) Al(OH)3(+) Electrolytes Precipitating value Electrolytes Precipitating value LICI 58 Nacl 43.5 KCI KCI 49.5 KNO3 60 0.65 K2SO4 0.30 Mgcl 0.72 K.Cro 0.63 MgSO4 0.81 (KOOC)2 0.69 AlCI 0.093 K,[Fe(CN)]0.08 Al(NO3)3 0.095 What can we learn from the resultsAs2S3 (−) Al(OH)3 (+) Electrolytes Precipitating value Electrolytes Precipitating value LiCl 58 NaCl 43.5 NaCl 51 KCl 46 KCl 49.5 KNO3 60 CaCl2 0.65 K2SO4 0.30 MgCl2 0.72 K2Cr2O7 0.63 MgSO4 0.81 (KOOC)2 0.69 AlCl3 0.093 K3 [Fe(CN)6 ] 0.08 Al(NO3 )3 0.095 Precipitating value: The lowest concentration of electrolyte ( in mmol dm-3 ) at which precipitation of colloid can be easily observed. (precipitating efficiency/power) 8.9.2 Precipitation of colloids by electrolytes What can we learn from the results?