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Does Your Tap Water Have Salt in It?

based on 16 ratings
Author: Beth Gilbert
Type

Physics

Grade Level

5th-8th Grades

Difficulty of Project

Medium

Approximate Cost

$20

Safety Issues
  • Handle battery with care.
  • Do not get battery wet.
Approximate Time Required to Complete the Project

1-2 Hours

Objective

To test if water is salty.

Project Goal

To test water to tell if it has salt content without having to drink it first.

Materials and Equipment

  • What materials are required?  
  • Buzzer
  • 9 Volt Battery
  • Masking Tape
  • 2 craft or wooden popcycle sticks
  • Aluminum foil
  • Plastic Cups
  • Salt Water (tap water and salt)
  • Paper and pencil

Material Availability

  • 9 volt battery and buzzer can be purchased at an electronics store.
  • Craft sticks may be purchased at a craft store or super center such as Wal-Mart.

Introduction

Is there salt in your water?  You can easily test this doing a simple science fair experiment.  Salt acts as a conductor. That's because when you add salt to water, the salt molecules dissolve in the water and break into smaller parts called ions. The ions carry electricity through the water. Fresh water doesn't have these ions. So it's harder for the electricity to move through the water. It doesn't complete the circuit, and the buzzer doesn't buzz if salt is not present.  Therefore, when attached to a battery and buzzer you will be able to determine if there is salt in your tap water, your bottled water, or you can even collect rain water.

Research Questions
  • Does your tap water have salt in it?
  • Will adding salt to water conduct electricity?
Terms, Concepts and Questions to Start Background Research
  • Electricity
  • Conductors

Experimental Procedure

  1. Gather your supplies.
  2. Have a plastic cup of tap water (label it).
  3. Have another plastic cup with water and salt added to it (label it).
  4. Next cover your two Popsicle/craft sticks with aluminum foil.
  5. Take your buzzer and tape the red wire of the buzzer to the positive (+). end of the 9 volt battery and the other end to the foil covered stick.
  6. Tape one foil-covered stick to the black wire of the buzzer while taping the other one to the negative (-) end of the battery.
  7. You are ready to use your saltwater tester!
  8. Put the tips of the metal in the saltwater about an inch apart.  Make sure they do not touch one another.
  9. The saltwater should act as wire connecting the metal sticks and completing the circuit making the buzzer buzz.
  10. Document your results.

Bibliography

  1. Easy Kids Science Projects "Cool Science Projects"
  2. PBS Kids "Saltwater Tester"
  3. Science Toys "Electrochemistry"
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