Household Acids and Bases

Introduction

Acids and bases are used in many branches of chemical engineering. Acids can be used to make plant fertilizers or to remove rust from metal. Bases can be used to make concrete or to clean bathtubs. Many common household solutions contain acids and bases. Acid-base indicators, such as litmus paper and red cabbage juice, turn different colors in acidic and basic solutions. They can, therefore, be used to show if a solution is acidic or basic. An acid turns blue litmus paper red, and a base turns red litmus paper blue. The acidity of a solution can be expressed using the pH scale. Acidic solutions have pH values less than 7, basic solutions have pH values greater than 7, and neutral solutions have pH equal to 7.

In this experiment, you will test the acidity of several common household solutions using three different methods: litmus paper, red-cabbage juice, and a Vernier pH Sensor attached to your LEGO NXT.

Objectives

In this experiment, you will

• Test household solutions with litmus paper.
• Test household solutions using red-cabbage juice indicator.
• Use a computer and an NXT to determine the pH values of household solutions.
• Classify household substances as acids or bases.
• Determine the different red cabbage juice indicator colors over the entire pH range.
• Use red cabbage juice indicator to test other household substances.