Do Water Molecules Have Space Between Them?
Initial Publication Date: September 9, 2009
Summary
In this chemistry lab, students investigate whether water molecules have any space between them. Students fill a glass with water all the way to the top. Then they see if they can add salt to their cup without the water overflowing. They will also see if it makes a difference if they use different temperatures of water. (hot and cold)
CollapseLearning Goals
Before starting this activity, students should predict what they think is going to happen when they add salt to an already full glass of water. They also need to predict if they think there will be a difference if they use hot or cold water. When they start the activity, students will observe what is happening when they add salt to the water. Students will also infer what they think is happening to the salt.
Context for Use
This activity would be best in a middle elementary grade classroom. (3rd-5th) The activity will take one class period. It is done in the chapter Matter and Its Properties.
Description and Teaching Materials
I would complete this experiment after teaching the students about the properties of matter. (including chemical and physical properties, weight, mass, volume, and density)
Materials: clear plastic cup, plastic/paper plate, water in a pouring container, paper towels, teaspoon, table salt
What to Do:
1. Set the cup in the middle of the plate. Fill the cup to the top with cold water. Continue to add water until the cup overflows and then stop.
2. Carefully soak up the water on the paper plate with the paper towels. Be careful not to bump the glass of water.
3. Fill the teaspoon with salt. Slowly add salt grains to the water in the cup. Add salt until the water overflows the top of the cup. You may need to add two to three teaspoons. Keep track of how much salt you add.
4. Repeat steps 1-3 with hot water.
Explain the Results
1. Observe: How much salt were you able to add to the cold water? Hot water? How is this possible if the cup was already full?
2. Infer: What would happen if you were to add a marble to the already full cup of water instead of the salt? What would happen if you were to add sugar to the already full cup of water?
This activity was adapted from Scott Foresman. (Scott Foresman Science (2006). See learning in a whole new light. Pearson Education Inc. Glenview, Illinois. p. 337E)
Materials: clear plastic cup, plastic/paper plate, water in a pouring container, paper towels, teaspoon, table salt
What to Do:
1. Set the cup in the middle of the plate. Fill the cup to the top with cold water. Continue to add water until the cup overflows and then stop.
2. Carefully soak up the water on the paper plate with the paper towels. Be careful not to bump the glass of water.
3. Fill the teaspoon with salt. Slowly add salt grains to the water in the cup. Add salt until the water overflows the top of the cup. You may need to add two to three teaspoons. Keep track of how much salt you add.
4. Repeat steps 1-3 with hot water.
Explain the Results
1. Observe: How much salt were you able to add to the cold water? Hot water? How is this possible if the cup was already full?
2. Infer: What would happen if you were to add a marble to the already full cup of water instead of the salt? What would happen if you were to add sugar to the already full cup of water?
This activity was adapted from Scott Foresman. (Scott Foresman Science (2006). See learning in a whole new light. Pearson Education Inc. Glenview, Illinois. p. 337E)
Teaching Notes and Tips
Remind students not to taste the salt and to use all materials appropriately. I have added to this activity by trying it with cold and hot water and having the students infer what would happen if they were to try this experiment with sugar.
Share your modifications and improvements to this activity through the Community Contribution Tool »
Assessment
Students will be assessed by teacher observation during group work.
Standards
Strand: Physical Science
Substrand: Matter
Standard: Solids, liquids and gases are states of matter that have unique properties
Code: 4.2.1.2.2
Benchmark: Describe how the states of matter change as a result of heating and cooling
Substrand: Matter
Standard: Solids, liquids and gases are states of matter that have unique properties
Code: 4.2.1.2.2
Benchmark: Describe how the states of matter change as a result of heating and cooling