Skim milk does not have a chemical formula because it is a colloid, or mixture. The only formulas that exist for it are for the individual solutes that make up its composition like proteins and fats.
Asked in Skim Milk
How is skim milk and skim powder separated from milk?
Skim milk is milk with all of the butterfat (cream) removed. The butterfat rises to the top, and is easy to skim off. The remainder can be removed by centrifuge. What is left is skim milk. It is powdered by the simple industrial process of evaporation. ...