Vernier Software and Technology
Vernier Software & Technology

Acidity Tester


Engineers use robots to do tasks that might be harmful to humans. One common example is working with hazardous chemicals. A hazardous chemical is one that could cause a negative health effect, such as cancer, lung damage, skin irritation, or even death. If a mixture contains at least 1% of a known hazardous chemical, it is classified as a hazardous material. Consequently, many common household solutions, such as paints, cleaners, inks, and dyes can be considered hazardous. An acid is sometimes considered a hazardous chemical, because it can cause severe burns if it gets in your eyes, nose, or skin. Not all acids are hazardous, however. Some acids, such as vinegar and lemon juice, are used in cooking to give foods their distinctive flavor.

This challenge is to build a sensor-controlled robot to test for acids. A robot of this type would be very useful if you were dealing with the possibility of dangerous acids in an area.

Design Requirements

In this project, you will design and build a mobile robot for testing the pH of a solution. Use a ceramic coffee cup or other relatively heavy container to hold the solution, since a lightweight container, like a Styrofoam® cup, might tip over. Have the robot approach the cup, stop when the touch sensor comes in contact with the cup, and then lower the pH Sensor. After a few seconds have your robot raise the pH Sensor, play a sound, and then back away from the cup. Your program should compare the pH value of the solution with a pre-defined limit. If the pH is less than 7, have the robot scream. If the pH is greater than 7, have the robot say “good.”

We recommend using orange juice or cola for the acid in this project and water with a little baking soda added to it for the base. If you use any other acid solution, use caution as they can be toxic, corrosive, or irritating to the skin, eyes, lungs, or mucous membranes. Handle those solutions with care. Do not allow the solutions to contact your skin or clothing.

You are strongly encouraged to use the Engineering Design Method and your creative imagination when tackling this challenge.

Sensors and Equipment

This project features the following Vernier sensors and equipment.

Additional Requirements

You will also need NXT Sensor Adapter and a LEGO MINDSTORMS NXT robotics system.

Standards Correlations

See all standards correlations for Vernier Engineering Projects with LEGO® MINDSTORMS® Education NXT »

Vernier Engineering Projects with LEGO® MINDSTORMS® Education NXT

See other experiments from the lab book.

1Acidity Tester
2Plant Waterer
3Aquarium Monitor
4Sunscreen Tester
5Audio Assistant
6String Tension Tester
7Cartesian Diver
8Battery Tester
9Solar Tracker
10Migrating Robot
11Magnet Finder
12Mine Sweeper

Project 1 from Vernier Engineering Projects with LEGO® MINDSTORMS® Education NXT Lab Book

<i>Vernier Engineering Projects with LEGO<sup>®</sup> MINDSTORMS<sup>®</sup> Education NXT</i> book cover

Included in the Lab Book

Vernier lab books include word-processing files of the student instructions, essential teacher information, suggested answers, sample data and graphs, and more.

Buy the Book

Dev Reference: VST0433

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