Lesson 6

Lesson Objectives...

• Apply key model ideas and patterns in mass and property data to construct three explanations for: a) why the mass of a system decreases when substances are mixed together, b) which substance(s) could or could not be produced in that process, and c) what additional tests could be done on the gas (or other gases) to help identify additional substances that aren’t being produced in this process.

Resources for Lesson 6...

Video # 1 - 

You watched the video of the elephant’s toothpaste, which was the result of combining three different ingredients together: potassium iodide (a substance), a mixture of hydrogen peroxide and water, and soap (a mixture).  

Video # 2 - 

Record your observations of this investigation.

What we figured out this lesson...

• The mass of a partially open system where potassium iodide and hydrogen peroxide are combined decreases because a gas is formed and some of it escapes the system.

• The gas produced makes a glowing ember burst into flame and an already burning flame glow brighter.

• Flammability data can help us identify the types of gases that aren't being produced in this process.

• Testing the melting/freezing point, density, and/or comparing the results of the flammability test to results from controls could help identify additional substances that aren't being produced in this process.