Posted: March 13th, 2017

The crystals are then seperated in the 1st stage filter and carry an adhering solution in the proportion : 0.058 lb solution/lb crystals.The separated crystals are then dried in a second tage to remove the remaining free ater (but not the water of hydration).

A water solution contains 62% Na2S2O2 together with 1.4% soluble impurity. The solutionis 1st diluted with water and then cooled to 10 Celcius where Na2S2O2.5H2O crystallises out.Yhe solubility of this hydrate at 10 celcius is 1.4 lb Na2S2O2.5H2O / lb free water.The crystals are then seperated in the 1st stage filter and carry an adhering solution in the proportion : 0.058 lb solution/lb crystals.The separated crystals are then dried in a second tage to remove the remaining free ater (but not the water of hydration).If the final dry Na2S2O2.5H2O crystals must not contain more than 0.18wt% impurity,calculate