pH+Rainbow


 * pH Rainbow POE **
 * Names and Contact Information: **

Corinne Brockel: ceb5192@psu.edu Hannah Nowotarski: hxn138@psu.edu
 * Grade Level and Topic: ** Grade 7, pH, pH indicators and Simple Acid/Base Reactions
 * Educational Standards: **
 * 3.2.7A: ** Explain and apply scientific and technological knowledge.
 * 3.2.7B: ** Apply process knowledge to make and interpret observations.
 * 3.4.7A: ** Describe concepts about the structure and properties of matter.
 * Instructional Objectives: **
 * 1) ** 1. ** Students should be able to identify how higher pH differ from lower pH.
 * 2) ** 2. ** Students should be able to explain the importance of simple acid/base reactions within chemistry.
 * 3) ** 3. ** Students should be able to explain the importance of pH indicators within acid/base chemistry.

The main point of this lesson is for students to explore the concepts of pH and their ranges. Not every compound has the same pH and they are huge factors in many reactions. The students will be able to identify the practical uses of pH indicators. By using the POE method, students will gain a basic understanding of pH indicators and their many applications.
 * Content Explanation: **

To make this lesson easier, we will break the students into different groups. Ms. Brockel will lead two of the groups and Ms. Nowotarski will lead the other two. Each group will be made up of four students. For safety precautions, there will be no hazardous materials available for students use in this lab. The main precaution is to tell students not to try drinking the chemicals within this experiment. Students will be provided with a POE sheet while the demonstration takes place.
 * Administrative Considerations: **


 * Materials needed: ** 4 beakers, 10 test tubes with rack, pipets, stirring rods, scoopulas, methyl red, bromothymol blue, cresol red, methyl red, 0.1 M HCl, 0.1 M NaOH, 6 goggles

Methyl Orange 3.1-4.4 Red Orange Bromothymol Blue 6.0-7.6 Yellow Blue Cresol Red 7.2-8.8 Yellow Reddish Purple Methyl Red 4.4-6.2 Deep Red Yellow
 * Indicators Transition Range Acidic Color Basic Color **


 * Lesson Plan **
 * Introductions, ask what students know about pH, acids and bases. Then discuss how pH indicators are used to determine if a solution is acidic or basic.
 * o pH indicators are often used to determine how far along a chemical reaction is
 * o pH indicators work best over their pH ranges
 * Exploration: Explain to students that we are going to look at the transition ranges of different pH indicators. First, the indicator will be added to neutral solutions of water (pH around 7-8), and students will be asked to record the color change. Then acid will be added to the beakers and the color change will again be recorded. Finally, base (2 times more than the acid added) will be added to the solutions, the color change will be recorded, and students will be asked to predict the transition ranges for each indicator (or at least rank them – ie methyl orange has an acidic transition range, cresol red is more basic).
 * Students will be asked to explain their predictions, and then will be presented with the actual transitions ranges for each. If their predictions don’t match, we will discuss this. A wrap up discussion of acids and bases and the uses of pH indicators will follow.
 * pH Rainbow **
 * Deep Red: **Acidic Methyl Red**
 * Red: **Acid Cresol Red and Methyl Orange**
 * Orange: **Basic Methyl Orange**
 * Yellow: **Acidic Bromothymol Blue and Acidic Methyl Red**
 * Green: **Neutral Bromothymol Blue**
 * Blue: **Basic Bromothymol Blue**
 * Purple: **Basic Cresol Red**
 * Pink: **Neutral Cresol Red**