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Can’t Judge a Powder By Its Color

Can’t Judge a Powder By Its Color. PART 2. Data. The competition: Data is to be recorded on a data sheet with a pen provided by the event supervisor. Data should be neat and organized Data should be numbered sequentially as it is collected. Data Sheet:. Flow Chart for testing sample.

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Can’t Judge a Powder By Its Color

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  1. Can’t Judge a Powder By Its Color PART 2

  2. Data • The competition: • Data is to be recorded on a data sheet with a pen provided by the event supervisor. • Data should be neat and organized • Data should be numbered sequentially as it is collected.

  3. Data Sheet:

  4. Flow Chart for testing sample

  5. Consistency • Encourage your students to be consistent with: • The size of the sample • The volume of water or any other liquid added • Perhaps, the container for testing

  6. Clean up period Short as possible, 5-10 min max. Leader should remind students about special wastes Leader collects pens and sample bags.

  7. Question Period Time remaining, 15-20 min Students should now have no pens or sample bags

  8. Question sheet • Question sheet: • When the questions and pencils are distributed, the supervisor will collect all samples. If the team has sufficient data and/or observations to support the answer to a question, they are to simply place the data number(s) beside the question. Place a number for all data that supports your answer.

  9. Question Sheet

  10. Data Sheet:

  11. How many questions? • Question sheet can also function as the scoring sheet. • 10-12 seems to be a good number. • Give students the opportunity to note what they think is their best observation, that has not been used to answer a question previously. • A question grading waste disposal and clean up of work area.

  12. The judge: will collect the samples and the pens. issue pencils. provide the students with the questions sheet Students will be told: to write and circle the question number in the column on the right hand side of the observation sheet Any remembered answers are to be written below the observations written in pen. The question number should be written and circled in the right hand column as before. Scoring the Event

  13. Value of Questions: • Each question is worth 5 points. The number of points awarded will depend on the quality of the data and/or observations. • If a team remembers the answer to a question, but does NOT have supporting data and/or observations, they may write the answer to question with their pencil and receive a maximum of 2 points.

  14. Scoring of Real Qst. • Qst: Is the powder • shiny, • dull, or finely divided? • How does the powder look? • Scoring: Written In Later • 3/3 =5 pts. 3/3 = 2 • 2/3 = 4 pts. 1 or 2/3 =1 • 1/3 = 3 pts.

  15. Student Responses: • Qst: Is the powder shiny, dull, or finely divided? How does the powder look? • 5 pts: white, airy, opaque, powdery, fine, non-clumpy, and solid • 4pts: white, compact, not loose, individual particles too small to see, dull finely divided • 3pts: white with no definite crystals

  16. Scoring of Real Qst. • Qst: What is the pH of solution when the powder is dissolved in water? • Scoring: Written in: (accepted) 5.5 • pH 5-6 = 5 5-6 = 2 • pH <5 =3 <5, >6 = 1 • pH >6 =3

  17. Student responses: • Qst: What is the pH of solution when the powder is dissolved in water? • 5 pts: pH of aqueous solution = 6 • 3pts: water = pH 7, no pH change of crystals and water

  18. Scoring Ties: • Ties will be broken by using the most answers that received 5, then 4, then 3 • All teams have a raw score of 30 5 4 3 2 1 0 • Team #1 = 3 1 2 2 1 7 • Team #2 = 3 1 1 • Team #3 = 2 2 3 1 1 7 • Team #4 = 1 1 4 3

  19. Thoughts: Practice, Practice, Practice • Use common solids • Size of sample • Supply water in a wash bottle • Is temperature worth it?

  20. Testing Various Powders • Across each spot plate • Water, 1M HCl, 1M NaOH, 2-propanol(isopropyl alcohol), methanol • Second row: pH paper • Third row: 2 drops Ca(NO3)2 2 drops Ba(NO3)2 2 drops AgNO3

  21. Testing Various White Powders Alum Aspirin Baking Powder Borax Chalk Citric acid

  22. Testing Various White Powders Epsom Salt Sugar Table salt

  23. Testing Various Colored Powders Copper sulfate Ferrous ammonium sulfate

  24. Summarizing:

  25. Thoughts: • Judge should have a MSDS sheet available for the powder • Safety is of the essence • Is it worth is it?

  26. Thoughts • Perhaps supply a third liquid to test solubility • Perhaps supply a test reagent solution to look for precipitates • For #3 and #4 decide about waste problems

  27. Thoughts: • Where is waste from the students work to be disposed? • What about clean up of work area? • If judging decide on a powder and become familiar with that powder

  28. In closing: • Gretchen Wolf may be contacted at: • Purdue University Calumet • GSWolf@calumet.purdue.edu • Or 219-989-2282 • This presentation is available at the following web site. • http://webs.calumet.purdue.edu/scienceolympiad/ • Many thanks for this opportunity. • Gretchen S. Wolf 10/01/04

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