Activity
How Water Changes State
This activity helps students to understand the adding and removal of thermal energy, during an introductory chemistry course.
This activity accompanies reading and discussions in an introductory chemistry or physical science course. Changes of state are physical changes. Although water and ice look different, they are the same kind of matter. Water can be frozen and then melted again. Melting, freezing, vaporization, condensation and sublimation are all physical changes.
The above picture shows a ring stand set-up holding the talking thermometer safely above the items that are hot. An additional ring could be added to hold the beaker.
Materials
- Paper coffee cups
- Water
- Freezer
- Beakers
- Ring stand
- Graphing materials
- Hot plate
- Talking thermometer
- Heat proof mitts
Preparation
Create a tactile and large print line graph illustrating the increases in water temperature and the increasing thermal energy as water changes state. We used an illustration in Matter and Change by Delta Education as a basis for our graph.
The graphs shown have arrows made of Wikki Stix TM, and tactile representations of the states of matter that were created on the PIAF machine.
For the boiling part of the experiment, set up the ring stand, hot plate and thermometer as illustrated in the picture. This ensures maximum safety for all.
Please follow all safety precautions in lab settings.
Procedure
Part 1 Freezing Point
- Fill sturdy paper cups approximately half full of tap water.
- Using a talking thermometer, record the temperature of the water after it has stood for several minutes to achieve room temperature. Record the data.
- Place paper cups, water and the thermometers in the freezer. Monitor the temperature changes every 15 minutes until the water changes to ice. Record your data.
- Remove the cups from the refrigerator and allow the temperature to gradually rise and the ice to melt. Record temperatures every 15 minutes.
- Transfer water to beaker that can be placed on a hot surface, such as a hot plate.
- Place beaker on the unheated surface of the hot plate in the ring stand. Place talking thermometer in the beaker. Turn on the hot plate.
- Record temperatures as they rise until water reaches the boiling point.
- Graph the collected data.
Compare the collected data to the tactile graph or graph in a text book OR create your own graph using tactile and large print materials.
Variations
- Activity can be easily modified to calculate freezing point depression and boiling point elevation by adding solute to the water before boiling or freezing.
NGSS Standards
- MS-PS1-4. Develop a model that predicts and describes changes in particle motion, temperature, and state of a pure substance when thermal energy is added or removed.
The graph featured in this article was created by Dan Moskowitz, Science Department Teaching Assistant.
By Kate Fraser
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