12. Concept Check! In your lab notebook, draw a large box. In this box, draw a molecular-level picture of a solution of barium nitrate ( 2 molecules) and sodium sulfate ( 5 molecules) in water before precipitation has taken place. In a second box, draw a molecular-level picture of the mixture after precipitation has taken place. Use simple circles to represent ions. B. Precision and Accuracy of Glassware for Measuring Liquids