Water lab

AP bio Blog Water Lab
Station 1:

 In this station droplets of water were dropped onto wax paper. When they were dropped they formed a little bubble on the wax paper instead of soaking into the wax paper like water normally would. This happens because the surface tension of the wax paper is stronger than the water, therefore the water forms the droplet. The entire water droplet is polar therefore it stays together. When a toothpick soaked in soap is put inside the water droplet, the water disperses because the soap is non polar. The two substances don't mix, so the water breaks its bubble that it was in.

Station 4:

                                                                         

 In this station there was a beaker of ice cold green colored water and another smaller beaker with room temperature water. When the ice cold water squeezed into the room temperature water on the BOTTOM, the water did NOT mix. This is due to the temperature moderation of the two liquids. Because of the hydrogen bonds that water has it is very resistant to temperature change, meaning water's temperature does not fluctuate easily. The two liquids therefore do not mix because their temperatures are so different. Also the cold water is denser than warm water so it stays on the bottom. In the second picture the ice water is squeezed on the TOP of the room temperature water and the water DID mix. The cold water is denser due to the hydrogen bonds and the warm water has loose molecules. Because of this the ice water floats down to the bottom.

Station 7:
 In this station Acetone was squirted on someones hand into a small puddle. At fist the chemical just sat on the hand but then all of a sudden is almost seemed to soak into the hand at a very rapid rate. What actually happened was the acetone molecules evaporated.  Acetone is a non polar chemical so the molecules do not stick together, thus moving around very quickly. By them moving around so much that makes them heat up. When they are heated up they being to evaporate from the hand into the air. This leaves the cooler molecules, water, which are polar so they stick together, behind. The cooler molecules left behind then eventually soak into hand or just stay on the surface