Class 3
Our homework before coming to class today was to listen to a slightly funny sounding video made by Mr. Quick on the properties of water. In class, we went over all the different characteristics of water, such as its molecular shape, polarity, cohesion/adhesion, and surface tension.
In order to demonstrate cohesion and adhesion, we did a small experiment involving coins.
We would slowly drip drops of water onto the coin so that it forms a groovy dome-like, hemispherical body of water over the coin. Mr. Quick told us that water forms a dome shape when its molecules cohere with each other because a water molecule's molecular shape is bent, therefore showing that when water is filled to the brim in a cup, there is a small smooth hump over the lip of the cup.
We then proceeded to dip a toothpick covered with dish soap into the water covered coin. The water spread itself out all over the table immediately. This phenomenon happens because dish soap breaks the surface tension of the water; the cohesion bonds between each molecule. From this experiment, we also learned why a water-strider can run across water; Their thin legs are light enough so that it does not break the bonds of the water.
Our homework before coming to class today was to listen to a slightly funny sounding video made by Mr. Quick on the properties of water. In class, we went over all the different characteristics of water, such as its molecular shape, polarity, cohesion/adhesion, and surface tension.
In order to demonstrate cohesion and adhesion, we did a small experiment involving coins.
We then proceeded to dip a toothpick covered with dish soap into the water covered coin. The water spread itself out all over the table immediately. This phenomenon happens because dish soap breaks the surface tension of the water; the cohesion bonds between each molecule. From this experiment, we also learned why a water-strider can run across water; Their thin legs are light enough so that it does not break the bonds of the water.
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