Preview - Pnom - Particulate Nature Of Matter

Exploration 3- Experiment

Consider the following experiment and its results. Then answer the questions below.

  1. A group conducts an experiment to test the rate of evaporation in a closed vs, and open system. They gather the following supplies:
    • a cup with a small bit of rubbing alcohol in it
    • a petri dish
    • two eyedroppers
    • a clock
  2. They fill two eyedroppers with rubbing alcohol and place two drops of alcohol on the table at the same time. They start the timer and immediately, cover one with a glass dish (see the photograph on the right)
  3. They check every 1 hour to see if either drop has evaporated completely. At 2 hours, drop B in the open system has evaporated completely, but drop A in the closed system has not.
  4. They continue for observing, now every hour, and at the end of the day (8 hours later), drop A still hasn't evaporated completely.
Substance & Condition Time to evaporate completely
Drop A: 1 drop of rubbing alcohol in a closed system       Unknown if it will happen at all, but if it does happen at some point it will take over 8 hours.
Drop B: 1 drop of rubbing alcohol in an open system        About 2 hours.

Questions

Please answer the questions below.

At 10 seconds after the experiment for each of the two conditions: Draw a model of the initial drop of liquid in a closed system after 1 hour.

At 10 seconds after the experiment for each of the two conditions: Draw a model of the initial drop of liquid in an open system after 1 hour.

Step 1 – You are going to create a molecular model of the drop of liquid evaporating.  A drop of alcohol has millions of billions of alcohol molecules in it.  This is too many for you to draw in a model.  So pick a reasonable number of molecules to represent in a drop of alcohol that you can draw quickly.

Step 2 - Draw a model to show the molecules of alcohol in a drop of alcohol. Include the same key as before, using circles to represent one type of molecule and hexagons to represent another type. 

Note: Draw your sketch in the sketchpad below

Notes

These notes will appear on every page in this lesson so feel free to put anything here you'd like to keep track of.