Exploring Phase Changes

Today, we expanded our knowledge of the states of matter by exploring how a substance can change from one state to another.  We call these phase changes.  Phase changes are very familiar to you, though you have probably not called them that.  Here is one example of a phase change:

Icicles

This video shows icicles forming over a period of 24 hours.  In this example, we see liquid water changing into solid ice as the temperature decreases over night.  This is a phase change.  When a liquid changes into a solid, it is called 'freezing'.  You can understand why I chose to show a video as an example of freezing rather than doing a demonstration.  (However, if someone can come up with an easy, inexpensive way to demonstrate freezing in the classroom, I may be able to offer some extra credit...)

The other examples of phase changes we showed were:
    Ice cubes sitting out a room temperature
    Steam  coming off of boiling water
    A tin can filled with cold water that had sweat on the outside of it
    Dry ice (the only non-water example and really fun to play with)

For each example, we analyzed the change we were seeing by collecting both qualitative and quantitative data.

Data Table

Over the weekend, I challenged everyone to find out what it is called when a solid changes directly into a gas without going through the liquid state.  Also, I asked if you thought it was possible for a substances to go the other way, directly from a gas into a solid.  If so, what is that called?

Chemical vs Physical Changes

Today, we learned about the difference between chemical and physical changes.  Here is a link to the close reading we did in class with the first page done for you as an example.

Bill Nye

Today in class, we started our chemistry unit by watching a video by Bill Nye (the Science Guy) about states of matter and phase changes.  If you weren't in class, here is the link to the video and the hand-out that goes along with it.  The questions come up pretty fast, so you have to really pay attention.