Education Technology

# Activities

• ##### Subject Area

• Math: Algebra I: Exponential Functions
• Math: Algebra II: Logarithms and Exponentials

9-12

60 Minutes

• ##### Device
• TI-73 Explorer™
• TI-83 Plus Family
• TI-84 Plus
• TI-84 Plus Silver Edition

TI Connect™

• ##### Accessories

CBL™/CBL 2™
Sensor - pH
TI Connectivity Cable
TI-GRAPH LINK™ Cable
Unit-to-Unit link cables
Vernier LabPro®

• ##### Other Materials
This is Activity 20 from the EXPLORATIONS Book:
Real-World Math Made Easy.

The following materials are required for this activity :
• Beaker
• Distilled water
• Lemon juice
• Eyedropper
• Effervescent antacid tablets

## Sour Chemistry: The Exponential pH Change

#### Activity Overview

In this activity, students' will use a pH sensor to record pH versus time data as an antacid tablet neutralizes acid in lemon juice. They will model the pH data with a modified exponential function.

#### Before the Activity

• Connect the pH probe to Channel 1 on the CBL 2™ or Vernier LabPro®
• Connect the CBL 2 or LabPro to the calculator using the Unit-to-Unit cable
• See the attached PDF file for detailed instructions for this activity
• Print pages 199 - 205 from the attached PDF file for your class
• #### During the Activity

Distribute the pages to your class.

Follow the Activity procedures:

• Place about 125 ml of distilled water in a very clean cup
• Place the pH sensor in the water
• Add drops of lemon juice to the water and stir gently
• Drop the effervescent tablet into the water and measure pH every 0/5 seconds for 50 seconds
• Plot the pH versus time graph
• Use a modified exponential equation to model the data
• #### After the Activity

Students will analyze data and complete the Data Collection and Analysis Sheet. They will also answer questions listed in it.

Review student results

• As a class, discuss questions that appeared to be more challenging
• Re-teach concepts as necessary