Is It Still Water? 

Introduction:

Water is one of the substances in our everyday life that changes state rather quickly and easily.  At room temperature water is a fluid substance that takes the shape of its container.  By heating the water to 100 degrees Celsius we can observe a change in state, from liquid to a gas.  This gas is not visible to the naked eye.  By lowering the temperature of the water to zero degrees Celsius we can observe its change to yet another state, a solid.  Ice is the solid form of water.  In this state water expands and holds its shape.  Because of how easily water changes state we will be using it to demonstrate changes of matter to the students.

 

National Standards Addressed:

The physical science standard of properties and changes of properties in matter is what this lab addresses.  It does this by showing students the various states of water and discussing the property changes that it undergoes.  As students witness these changes in matter they will gain a better understanding of the three states of matter.

 

Objectives and Benchmarks:

The purpose of this lab is to demonstrate to students the three states of matter that water exists in.  At the end of this lab students will be able to identify the three states of matter and explain how water gets to these states.

 

Materials:

Ice       Beaker            Bunsen Burners                 Thermometer            Plastics Sandwich Bags

 

Procedure:

The students should acquire ice and place it in a beaker.  Have the students observe the ice and write down at least three characteristics.  Students should place a thermometer against the ice and measure the temperature.  With a Bunsen burner have students gently melt the ice to a liquid state.  Remove the heat and have the students again take the temperature and write down three more characteristics.  Once again have students light the Bunsen burners and bring the water to a boil.  The students should take the temperature and record it in their notes.  Once the water begins to boil the students should hold the baggie over the burner and try to catch the steam as it rises off the burner.  Have them continue to boil the water until no more water is in the beaker.  Students should observe the condensation that has formed in the baggie.  This is direct proof that the water changed from a liquid to a gas and then cooled back to a liquid.  You may want to place the students condensed water in the freezer until the next class to return it back to a solid.

 

Things to Consider:

How do you know a change of state took place?

What needed to be added or taken away to make the change happen?

 

Possible Integration:

This lesson is primarily a physical science lesson; however, it can be integrated into a chemistry lesson by talking about the various molecular formations of the ice, water and water vapor.

 

Critical Concepts:

Solid    Liquid               Gas            Condensation               Evaporation