Untitled

**EIGHTH GRADE MATHEMATICS**
The students will predict the arrangement of various common household solutions as they would appear along the pH scale, determine the accuracy of this arrangement by analyzing a scatter plot generated by a CBL and graphing calculator, and rearrange the solutions appropriately to record their values along the pH scale.

**Teacher Information**
Benchmarks N.1, N.2, N.6, A.3, A.4, A.5, D.1, D.2	Time Frame 1-2 class periods
Curriculum Integration rational numbers, number lines, real data, tables, scatter plots, pH	Materials Per Group: graphing calculator, CBL, pH probe, 2 solutions of known pH, distilled water in wash bottle, lab tissue for instruments, 10 common household solutions, 10 plastic cups (6-8 oz.), marker, Sheet 1
Applications chemistry, lab technology, swimming pool maintenance	Student Groupings 3-4 students with the roles of cup handler/probe dipper, recorder, calculator operator, CBL operator

**Possible Obstacles to Student Learning**
understanding the pH scale developing graphing calculator and CBL skills understanding scatter plots

**Opportunities for Assessment**
Group Project: Students collect solutions from home and determine their pH values. Students will devise a dichotomous key for categorizing these solutions. The students will present their findings to the class. Journal Entry: Explain how the scatter plot indicated that your first ordering of the solutions according to their pH was either correct or incorrect. Research Project: Have students research the applicability of pH in the real-world and present their findings in a written report.

**Lesson Procedure**
Students must first label each of the ten plastic cups with the names of the ten common solutions. Each cup should be filled approximately half-way with the appropriate solutions. (If time is an issue, cups can be prepared for the students in advance.) Together the students must decide how to arrange the cups in order from most acidic to most basic(alkaline) as they would appear along the pH scale. The cup handler will physically arrange the cups and record the names of the solutions in the order of which the group has arranged them using the table provided on Sheet 1. Now each group will need to calibrate the CBL equipment using the ChemBio program. Once the calibration has been completed, the cup retriever will bring one cup at a time, in the order which they were arranged, to the probe dipper. A pH reading will be taken on each solution but not recorded. A scatter plot of the pH data collected should be generated on the graphing calculator. Next the students will determine the accuracy of their arrangement of the solutions along the pH scale by analyzing the scatter plot. It should be concluded that the scatter plot should form an increasing arrangement. The group must retrieve the actual pH value of each solution using the trace function on the graphing calculator. These values should be recorded on the table provided on Sheet 1. The students must then rearrange the cups using their actual pH values and graph this information along the pH scale along with their corresponding pH values.

Attachments

SHEET 1
SOLUTION POSITION	SOLUTION NAME	pH VALUE
1
2
3
4
5
6
7
8
9
10

1. What does the scatter plot indicate about your ordering of the solutions?

2. What should the scatter plot look like? Explain why.

**Exploration and Extension**
Have students analyze the graph produced by the changing pH of an antacid tablet dropped into a cup of tap water. Have students titrate antacid liquid (regular and double strength) into a small amount of lemon juice to determine the different effects of the antacids on stomach acid. Have students test the pH of various water sources such as a swimming pool, tap water, distilled water, etc.