Summary

In this lab, students will recognize that oxygen has mass and that heating can involve and increase in mass as an element reacts to become an oxide. The lab also introduces the idea that the relative mass of elements in a compound is in the same proportion as the atoms in the chemical formula. Read more about this experiment in Chemistry Solutions.

Grade Level

High school

Objectives

By the end of this lesson, students should be able to

• determine the chemical formula from collected data.
• recognize they carried out a synthesis reaction.

Chemistry Topics

This lesson supports students’ understanding of

• Chemical formula
• Synthesis reaction
• Law of Definite Proportions

Time

Teacher Preparation: 30 minutes

Lesson: one class period

Materials

• Bottle cap crucibles (2)
• Nichrome wire
• Bunsen burner
• Tongs
• Magnesium ribbon
• Clay triangle
• Ring stand
• Balance
• Ruler
• Pencil

Safety

• Always wear safety goggles when handling chemicals in the lab.
• Always be aware of an open flame. Do not reach over it, tie back hair, and secure lose clothing.
• Students should wash their hands thoroughly before leaving the lab.
• When students complete the lab, instruct them how to clean up their materials and dispose of any chemicals.

Teacher Notes

• To prepare the alternative crucibles, first heat the steel bottle caps over a Bunsen burner flame to remove the plastic insert. Allow to cool thoroughly before using.
• Extension: Magnesium reacts with nitrogen to form magnesium nitride (Mg₃N₂), which reacts with water to produce ammonia (changes moist red litmus paper to blue).

• View a video of this experiment in its entirety, including the extension.