1. Line a Petri dish with filter paper. 2. Place the petri dish on the electronic balance and zero it. 3. Add about 10 drops of acetone to the petri dish and measure the mass immediately. 4. Observe how the mass changes over time. (Create a scene in which the mass decreases over time from the initial mass to 0 g.) Why does the mass decrease? Because the liquid acetone particles on the surface of the acetone become a gas and evaporate into the air. 5. (Result) As the acetone dries, the scale on the electronic balance gets smaller and smaller until it reaches zero.