Summary

In this lab students will learn about the chemical reaction, oxidation, using apple wedges. They will apply different substances to a number of apple wedges to determine if these applications have any impact on the oxidation process. Students will also use a control sample so that they compare their results with an apple wedge that has not had any substance added to it. Students will measure and record the time it takes to see the changes to the apple which indicate oxidation.

Grade Level

Elementary School

Objectives

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

• Understand the meaning of oxidization and be able to identify the changes in apples that signify this chemical reaction.
• Identify which substances impact the process of oxidization.
• Measure and record observations.

Chemistry Topics

This lab supports students’ understanding of

• Chemical reaction
• Chemical change
• Oxidation
• Observations

Time

Teacher Preparation: 15 minutes

Lesson: 30 minutes

Materials (per group)

• 1 apple
• 1 apple core slicer
• Cup with ½ cup of water
• Cup with water and salt (1/2 cup water and 1 tbsp salt)
• Cup with water and sugar (1/2 cup water and 1 tbsp sugar)
• Cup with lemon juice (1 lemon squeezed into a cup)
• 5 Stopwatches
• Pencil
• Recording Sheet

Other for teacher:

• Measuring cups (1/2 cup)
• Measuring spoons (1 tbsp)
• Marker

Safety

• Do not consume lab solutions, even if they’re otherwise edible products.
• Food in the lab should be considered a chemical not for consumption.
• Always wear safety goggles when handling chemicals in the lab.
• Students should wash their hands thoroughly before leaving the lab.

Teacher Notes

• To prepare the solutions for each group:
  • Mix half a cup of water with one tablespoon of salt, place solution in a cup and label it.
  • Mix half a cup of water with one tablespoon of sugar, place solution in a cup and label it.
  • Cut lemon and squeeze juice into a cup and label it.
  • Fill one cup will have half a cup of plain water.
• It is recommended to have 5 students per team in order for each student to be observing and recording a wedge.
• This lab can be performed by any elementary grade level as instructions and procedures are basic.
• The average time it takes for an apple to oxidize with no solution is 5-10 minutes. Apple wedges with solutions can vary and can take up to 20 minutes.
• Oxidation is the loss of electrons or an increase in oxidation state by a molecule, atom, or ion.
• When an apple is cut (or bruised), oxygen is introduced into the injured plant tissue, this produces a chemical reaction that creates the brown color commonly seen. This change in color is the indication that oxidation is occurring.
• I recommend that teachers show this video after the lab is completed to explain the science behind the chemical changes the students will be observing.