Shampoo Woo, by Cindy Anderson and Matthew Dornier. Chemistry. Materials

Transcription

1 Louisiana Curriculum Framework Content Strand Chemistry Grade Level 9-12 Objective: The students will Perform lab investigations to determine the ph of shampoo Determine which shampoo, based on ph, is best Construct graphs and data tables Benchmarks SI-H-A1, SI-H-A2, SI-H-A3, S1-H-A7, PS-H-D2, SI-M-A1, SI-M-A2, SI-M-A7, SI-M-A8 Curriculum Integration Teacher Information Time Frame 2 50 minute class periods 1- lab and 1- graphical analysis Materials Safety, laboratory procedures, laboratory reports, scientific method, acids and bases, ph. Cross-curriculum integration: Math graphing Language lab reports, social skills Applications Chemical engineering, chemical make-up of solutions, shampoo consumer Several different types of shampoo Vials to hold shampoo CBL TI-83 Plus calculator ph probe 4 wooden splints 4 test dishes 20 strands of the same type of hair 4 strips of tape standard ph solutions (neutral; ph 2.0; ph 6.0; ph 10.0; ph 12.0) microscopes safety goggles deionized water beaker for rinse Student Groupings Cooperative groups Possible Obstacles to Student Learning Prior background on ph, acids and bases, graphing, use of the technology. Opportunities for Assessment 1. Cooperative laboratory reports: students will write a laboratory report for both the exploration and application activities. 2. Questioning during Concept Development. 3. Mid-term and/or Final Exam: students are held accountable for the manipulation of the equipment in a laboratory practicum.

2 Lesson Procedure Exploration: Students will be given a set of materials (ph probe, CBL) and different shampoo brands. Students will determine the ph of each shampoo. Students will test hair samples in different solutions of different ph. Students will graph results with the calculator and MS excel. Concept Development Questions with anticipated responses: Were most shampoos acidic or basic? Most shampoos were acidic. Which shampoo was the most acidic? Explain. Herbal Essence was the most acidic shampoo, because it had the lowest ph number. At what ph is hair the healthiest? Explain. Hair is the healthiest at a ph of 6. At this ph, hair is not as hard. It issmooth, resilient, and resists breaking. Integration of Technology: Student will test the substances with the CBL, graphing calculator, and ph probe. See laboratory procedure in student handout. Concept Application: Students will investigate which acid is in each shampoo that affects the ph. Attachments 1. Student Handout 2. Assessment Rubrics 3. Sample Data 4. References

3 Student Handout Purpose: Which ph is the best for hair? Materials: 5 vials containing different types of shampoo CBL TI-83 Plus calculator DIN adapter Link cable ph probe 4 wooden splints 4 test dishes 20 strands of the same type of hair 4 strips of tape standard ph solutions (neutral; ph 2.0; ph 6.0; ph 10.0; ph 12.0) microscopes safety goggles deionized water beaker for rinse Procedure: Part I 1. Prepare the ph system for data collection. Plug the ph amplifier into the adapter cable in Channel 1 of the CBL System. The ph electrode is already connected to the ph amplifier. Use the link cable to connect the CBL System to the TI Graphing Calculator. Firmly press in the cable ends. 2. Turn on the CBL unit and the calculator. Start the CHEMBIO program and proceed to the MAIN MENU. 3. Set up the calculator and CBL for ph measurement. Select SET UP PROBES from the MAIN MENU. Enter 1 as the number of probes. Select PH from the SELECT PROBE menu. Enter 1 as the channel number. Select USE STORED from the CALIBRATION menu. 4. Set up the calculator and CBL for data collection. Select COLLECT DATA from the MAIN MENU. Select MONITOR INPUT from the DATA COLLECTION menu. Press ENTER after the system has warmed up for 30 seconds. The ph reading is displayed on the screens of the CBL and the TI calculator. No readings are stored when using the MONITOR INPUT mode. 5. Raise the ph probe from the electrode solution and set the solution aside. Use a wash bottle filled with distilled water to thoroughly rinse the ph probe. Catch the rinse water in a beaker. 6. Get one of the 5 types of shampoos in the vials. Lower the ph probe into the solution. When the ph reading stabilizes, record the ph value.

4 7. Prepare the ph probe for reuse. Rinse it with distilled water from a wash bottle. 8. Determine the ph of the other solutions using the Step 6 procedure. You must clean the ph probe between tests, using the Step 7 procedure. When you are done, rinse the probe with distilled water and return it to the electrode solution. Press + to quit MONITOR INPUT. 9. Complete the data table attached. Part II: Treating hair samples in solutions of varying ph Complete the following activity in your lab group and answer the questions that follow. Procedure: 1. Obtain 4 wooden splints; 4 test dishes; 20 strands of the same type of hair; and 4 strips of tape. 2. Clean the 4 dishes in ph neutral solution and rinse thoroughly with distilled water. (Be sure to clean all glassware after each use so that the samples are not contaminated.) 3. Label the test dishes ph 2.0, ph 6.0, ph 10.0, and ph Add 10 ml of the appropriate ph solution to each of the dishes. 4. Tape 5 strands of hair to each splint with one end fastened, and the other end free to be immersed in the test solutions. Label the ends of each splint with ph 2.0, ph 6.0, ph 10.0, and ph Put each splint into the corresponding solution. Allow the hair to be exposed for 10 minutes. 6. Remove the hair sample and rinse with distilled water. Allow the strands to air dry. 7. Grasp the ends of the ph 2.0 sample and pull gently. Record observations of the following in the data table: texture (e.g., rough, smooth) and resilience (hairs ability to stretch and contract without breaking). 8. Observe the hair under the microscope. Sketch what you see and record notable observations in the table (e.g., texture, smoothness). 9. Repeat for other samples. Part III 1. Use data obtained from part I to construct a graph on the TI-83 calculator and MS Excel. 2. Print out graph from TI-83 using TI Graph Link. Label properly. 3. Print out graph using MS Excel.

5 ANALYSIS Part I: Determining the ph of shampoo samples Using the shampoo samples given to you by your teacher, determine the ph of each of the samples using the ph probes. Shampoo name ph Part II: Effect of ph on Hair Resilience ph Treatments Texture Resilience Sketch of Hair ph 2.0 ph 6.0 ph 10.0 ph 12.0

6 Analysis Questions: 1. Were most shampoos acidic or basic? 2. Which shampoo was the most acidic? Explain. 3. At what ph is hair the healthiest? Explain. 4. Compare and contrast using TI Graph Link to using MS Excel to print graph of data.

7 Assessment Rubric Category Safety Lab activity was completed with no errors and safety equipment was used properly. Lab activity was completed with minor errors, but safety equipment was used properly. Lab activity was completed with minor errors and some safety equipment was used improperly. Data Analysis Graphs Participation Table is complete with proper labeling and ph values are approximate to correct value. Writing is neat and legible. Questions are answered correctly and trends are identified. Sentences are complete and legible. correct with proper labels. neat and legible. Cooperated with other group members. Completed job without any errors. Actively participated in answering questions. Table is complete with proper labeling and ph values are approximate to correct value. Questions are answered correctly. Sentences are complete and legible. correct with proper labels. Cooperated with other group members. Completed job without any errors. Table is complete with proper labeling. ph values are not within a suitable range. Questions are answered correctly. correct without proper labels. Cooperated with other group members. Completed job with minor errors. Lab activity was completed with major errors and safety equipment was used improperly. Table is incomplete with improper labeling and ph values are not within a suitable range. Questions are answered incorrectly. incorrect with improper labels. Did not cooperate with other group members. Incomplete job with major errors.

8 SAMPLE DATA Fig. 1:1 ph of Shampoos ph units Head & Shoulders Pantene Herbal Essence Finesse Prell Shampoo Brands

9 References 1. Louisiana Department of Education (1997). Louisiana Science Framework, Retrieved December 13, 2001, from the Louisiana Department of Education website Holmquist, D. Chemistry with CBL. Vernier Software to Science NetLinks (2001). The Chemistry of Hair Care, Retrieved June 18, 2002, from the Science NetLinks website.