Lab

Summary

In this lab, students will test four unknown substances to identify which is water by conducing chemical and physical changes on the substances. They will determine what tests need to be carried out to differentiate the liquids. To earn supplies, they will carry out review problems.

Grade Level

Middle school

Objectives

By the end of this lesson, students will

• identify characteristics or water.
• design and conduct experiments.
• analyze data and draw conclusions.

Chemistry Topics

This lesson supports students’ understanding of

• Physical changes
• Chemical changes

Time

Teacher Preparation: 40 minutes

Lesson: 86 minutes

Materials

For each group:

• One paper towel
• One piece of wax paper
• Penny
• Toothpick
• Eye dropper
• Paperclip
• Popsicle stick
• Plastic cup

Items to be earned:

• Sugar
• Pepper
• Mentos
• Dish soap
• pH probe
• pH paper/key
• Baking soda
• Graduated cylinder
• Electronic balance

Liquids to be tested (can choose any four of the following):

• Vinegar
• Water
• Corn syrup
• Colorless beverages
• Rubbing alcohol
• Hydrogen peroxide
• Mineral oil

Safety

• Always wear goggles when working in a lab setting.
• It’s important to emphasize that even though students are trying to identify water, other chemicals could be harmful. Taste testing is not a suitable way to investigate the identity of their substances.
• 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

• This activity is an adaptation of the Project WET lesson “Water on Zork” (1995).  I adapted the lesson to be used as a lab practical at the end of our chemistry unit.
• In the days prior to the activity, I built student anticipation by discussing the upcoming trip to Zork. I also used Blabberize to create a newscast about the students being stranded on Zork.
• I set up one lab kit for each group and prepared the colorless liquids by numbering them and making a teacher’s key.  Clues and aliens were also prepared in advance and placed around the lab.
• I write various tasks on alien cutouts and if the students can accomplish the task, they earn equipment. 
  • If students can balance an equation they are given pH paper.  They soon realize that the pH paper does not do them much good without the color key, so they must balance another equation to earn the key. 
  • Students may draw Bohr diagrams, list various products and reactants in equations, and answer questions about material we reviewed in class. 
  • Phase changes can also be included in the experimentation process.

• I hide the clues around the room and add to the challenge by telling students that if their table is left completely unattended, their materials may be taken back by the aliens. 
• Between day one and day two I add new clues based on student suggestions.  I also move clues to new locations and take some clues away. 
• Students are required to re-earn items they used the day before.

Downloads

• Teacher Guide.doc
• Teacher Guide.pdf
• Student Activity.doc
• Student Activity.pdf

Submitted by
Jennifer Smith
Monticello Middle School Monticello, Illinois
 

For the Student

Is There Water on Zork?

Lesson

Background

Your space shuttle has crashed on the planet Zork.  You and the rest of your crew were able to eject from the shuttle before it crashed, and you landed safely on a small island.  Unfortunately, you have no supplies and the only equipment you have with you is your space manual (science notes) and a small experiment kit. It will be four days before a rescue team can make it to your location and since Zork gets very hot during the day, you will need water before then. For your crew to survive, you must find water before the end of your second day on the planet. You have located four different substances that appear to be water, but you need to know for sure which one is water. Your mission is to design and implement various tests in order to determine which liquid is water. DO NOT PERFORM TASTE TESTS!

Materials:

• Apron
• Goggles
• One paper towel
• One piece of wax paper
• Penny
• Toothpick
• Eye dropper
• Paperclip
• Popsicle stick
• Plastic cup
• Other materials as students deem necessary

Procedure/Results

PART 1: Observations of Water

Think back to your time on earth and make a list of the characteristics of water.  For each characteristic please note whether it is a physical property or a chemical property.

PART 2: Observations of Samples

In the chart below, list the letter of each sample and note what you observe about the sample.

PART 3: Initial Hypothesis

Look at the information in your chart for part 2. On the basis of your initial observations, come to a consensus on which sample the group thinks is the water. Write which sample you think is water and provide evidence for your thoughts.

PART 4: Experimentation

Now that you have observed each of the samples, it is time to develop and conduct experiments. As a team, you will develop and conduct at least two different tests of the samples. Explain your reasoning for each test then write out the materials and procedure for each test and create a data table for your results.

          Test 1:

                   Materials:

                   Procedure:

                   Data Table:

          Test 2:

                   Materials:

                   Procedure:

                   Data Table:

          Optional Test 3:

                   Materials:

                   Procedure:

                   Data Table:

Analysis

1. Which sample was water? Write a paragraph using the data from your experiments as evidence to support your conclusion.
2. Write a paragraph describing the manner in which you used the scientific method during this investigation.

Extra Credit

Complete the table listing the names of the other samples.

Connections to Standards

NGSS: MS-PS1 Matter and Its Interactions

• Disciplinary Core Ideas: PS1.A: Structure and Properties of Matter, PS1.B: Chemical Reactions
• Science and Engineering Practices: Asking Questions and Defining Problems, Planning and Carrying Out Investigations, Analyzing and Interpreting Data

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