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You need your lab notebook!!

You need your lab notebook!!. A note on assignments. Late homework is worth 50%. I will not stamp the date on it. BE ORGANIZED!! Keep your notebooks in one place (on your shelf). Keep a separate notebook for each class.

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You need your lab notebook!!

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  1. You need your lab notebook!!

  2. A note on assignments • Late homework is worth 50%. I will not stamp the date on it. • BE ORGANIZED!! Keep your notebooks in one place (on your shelf). • Keep a separate notebook for each class. • You are in 10th grade. It is YOUR responsibility to complete assignments on time and to not lose your things.

  3. Studying • Flashcards • Self quiz • Quiz a friend • Teach a friend from memory • Draw and label diagrams from memory • Rewrite notes • Make up practice quiz questions

  4. Retaking a quiz • Tuesday 8:10-9:00 pm • Thursday 7:00-8:00 pm • Call from desk, 2nd floor: 814 • I will give you the higher mark

  5. Separation of a Mixture 16 Oct. 08 • Objectives: 1. • 2. • Techniques: 1. • 2. • Materials • (skip 5 lines) • Procedure: Observations: • Find the mass…

  6. Separation of a mixture

  7. Objective • To separate a mixture of manganese dioxide and sodium chloride. • To determine the percent of each obtained after the separation, and the percent error.

  8. Compounds • manganese dioxide, MnO2, insoluble black powder (manganese (IV) oxide) • sodium chloride, NaCl, soluble white crystals

  9. Technique • Filtration • Evaporation

  10. Filter paper funnel

  11. Desiccator (removes water from a sample) Stirring rod

  12. Weighing paper Drying oven (removes water from a sample quickly)

  13. beaker

  14. Alcohol burner Ring stand/ring

  15. Spatula (for moving powdered chemicals from their containers) Evaporating dish

  16. Procedure • Find the mass of the 100 mL beaker on the electronic balance. • Mass 2 grams of NaCl and 1 gram of MnO2 on weighing paper, and record their initial masses. Mix them together in the beaker. • Add 20 mL distilled water to the NaCl and MnO2 mixture. Swirl gently to mix, until all the NaCl is dissolved. Record a qualitative description. How would you separate this mixture (and record the mass of each compound after separation)?

  17. Equipment • Beakers(2, 100 mL), electronic balance (1), distilled water, graduated cylinder (1, 100 mL) • NaCl (powder, 2g), MnO2 (powder, 1 g)

  18. Homework 1 • Draw a cartoon of the SIX main steps required to separate this mixture, • and to find out the mass of each compound collected at the end. • Write a sentence to describe each of the six steps, under each box of the cartoon. • Due: Fri.

  19. Goals: Separate the manganese dioxide from the NaCl. • Find the mass of each compound after the separation, and compare it to your initial masses. • Calculate your percent error.

  20. Homework • Due Thursday (with your cartoon) • On a separate piece of paper: • Write the procedure for separating these two compounds (don’t worry about collecting the water)and calculating % obtained/%error. • Write a list of materials and equipment required (include how many of each).

  21. A good procedure… • Very specific – list every detail even if you think it is obvious! • In the correct order • Give the name of each piece of equipment you use • Write when you will make observations or take a measurement • Describe how to do each calculation

  22. If you do not turn in this assignment, you will not be allowed to participate in lab. • We will edit your procedures before going to lab. • Do your best…draw pictures if you have a hard time writing sentences. • Come see me for help!

  23. Process of Separation Mixture Suspension Filtration Residue – manganese dioxide Solution Reacts with HCl acid, turns moist KI paper blue Evaporation Solute – sodium chloride Water Reacts with AgNO3 solution to form white precipitate

  24. Qualitative Observations:

  25. Common Challenges Add to your procedure to fix these problems!!

  26. When filtering • How will you keep salt water from being absorbed by your filter paper?

  27. Wet the filter paper with distilled water from the wash bottle before filtering.

  28. When evaporating • How will you know when all the water is evaporated?

  29. When the salt looks dry, mass the dish + salt. Heat it a little longer, and mass it again. Repeat, until the difference in mass is less than 0.01 grams.

  30. When finding final mass • Scraping the NaCl from the evaporating dish and the MnO2 from the filter paper onto weighing paper will cause you to lose a LOT of mass. How can you avoid this?

  31. Mass the filter paper and evaporating dish at the beginning. At the end, mass the filter paper + MnO2 and the evaporating dish + NaCl. Then, just subtract!!

  32. Calculations • The procedure MUST show how to find the final mass of NaCl and MnO2. • Also describe how to calculate % obtained (the percent of each at the end), and % error.

  33. Homework • Write a final draft of your procedure in your lab notebook (in the left column). • Under “Materials,” list all the pieces of equipment and compounds, including how many/how much of each. • Due Thursday, 30 October, in lab • No procedure = no lab

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