Susan makes the following entry in her notebook: “On Friday we were given a blue liquid in a shallow container. We placed it on the windowsill over the weekend. On Monday morning, there was no liquid left, but the dish had some solid blue stuff in it.”

a. Was the blue liquid in the dish a heterogenous mixture, a solution, or a pure substance? Explain your choice.

b. Write a few sentences about what you think happened in the dish.

a. From the information provided in the question, the blue liquid is a solution. This is because a solution is a type of homogeneous mixture (that has an evenly distributed solute in a solvent) which is the reason the liquid was said to be blue (and not immiscible blue solid in a liquid) but after been exposed to heat became just a blue solid. Typically, a solution has a solute and a solvent (combined), the solute here is the blue solid while the solvent is the liquid that made the combination a liquid.

b. Since the dish containing the liquid was placed on a windowsill, it can be assumed that the dish was subjected to heat from the sun which caused the liquid (in the solution) to evaporate after exposure to the heat from the sun (over the weekend) leaving the blue solid solute (of the solution) to remain in the dish. This can be referred to as evaporation to dryness in separation techniques (if the goal was to intentionally separate the solid solute from the liquid solvent).