A water solution have 64% Na₂S₂O₂  together with 1.0% soluble impurity.  Upon cooling to 5°C, Na₂S₂O₂·5H₂O. crystallizes out.  The solubility of this hydrate is 1.35 lb Na₂S₂O₂·5H₂O per lb free water (water not bound in the hydrate),  The crystals teke away carry as adhering solution 0.06 lb solution/lb crystals.  When dried to took away the remaining water (but not the water of
hydration), the ?nal dry Na₂S₂O₂·5H₂O crystals must not have more than 0.1% impurity.  To meet this speci?cation, the original solution, before cooling, is further diluted with water.  In order to make 1000 lb's of dry crystal (hydrated), how many pounds of feed are required?  (Hint:  This problem is best solved using a spreadsheet.   Help on the spreadsheet will be available
Thursday in recitation - but do not wait until then to attempt the problem!)   The spreadsheet will be graded on how well it solves the problem and the quality of presentation of the spreadsheet and the work.  (Additional hint, the problem is simpler to solve if you track some "pseudo" components such as "free" water or "hydrated" crystals.  Sketch a picture of the process breaking it into small steps.  Have the spreadsheet do the calculations for every step for all components, real and "pseudo".  By changing the amount of water you add at the start your spreadsheet should display you the results in the ?nal product.)