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Why do we have them?

Why do we have them?. When we measure things, we want to measure to the place we are sure of and guess one more space. So, they show the uncertainty in our measurements.

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Why do we have them?

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  1. Why do we have them? When we measure things, we want to measure to the place we are sure of and guess one more space.

  2. So, they show the uncertainty in our measurements

  3. Since the marks on this ruler are subdivided as they are, our answer for the length of this nail has 3 significant figures.

  4. However, we only have significant figures when we are measuring something. Counting will give you an exact number.

  5. Lab Equipment

  6. Beaker • Holds chemicals during mixing, heating, and storage • Acts like a bowl • Inaccurate measuring device

  7. Erlenmeyer Flask • Holds chemicals during mixing, heating, and storage • Acts like a bowl • Inaccurate measuring device

  8. Volumetric Flask • Holds chemicals during mixing and storage • Accurate measurement of a specific volume

  9. Funnel • Aids in pouring and filtering process

  10. Watch Glass • Acts as a cover during heating and storage • Looks like a giant contact len

  11. Evaporating Dish • Container used to allow materials to evaporate

  12. Crucible and Cover • Used to hold materials that need to be heated to higher temperatures

  13. Crucible Tongs • Used to hold heated crucibles

  14. Bunsen Burner • Used to heat materials

  15. Striker • Used to light burners

  16. Balance • Used to determine the mass of materials

  17. Graduated Cylinder • Used to measure liquids accurately • Must look at meniscus of the liquid when taking readings

  18. Iron Ring • Attaches to ring stand • Holds various equipment while they are heated

  19. Buret Clamp • Attaches to ring stand • Holds burets during titrations

  20. Utility Clamp • Attaches to ring stand • Holds various thin equipment while they are heated

  21. Goggles • Protect eyes during experiments

  22. Ring Stand • Used to support devices during laboratory procedures

  23. Buret • Used to accurately and slowly add liquids • Used most often in titration experiments

  24. Thermometer • Used to measure the temperature of various materials

  25. Gas-collecting tube • Tube used to collect gases. • Usually used in the inverted position

  26. Test Tube • Used to hold small samples during heating and storage

  27. Test Tube Rack • Used to hold multiple test tubes

  28. Test Tube Holder • Used to hold one test tube, usually during heating or transporting test tube

  29. Forceps • Used to pick up and separate small solids

  30. Spatula • Used to scoop small quantities of solids • Can be used to scrape the inside of various equipment

  31. Mortar and Pestle • Used to crush and grind materials

  32. Pipet • Used to dispense small quantities of liquids

  33. Stoppers • Come in various sizes • Used to block openings of various equipment

  34. So, let us practice with reading different pieces of equipment

  35. Scales 622.89 g 153.70 g 200.54 g 128.192 g 205.548 g 90.900 g Answer to Worksheets

  36. Liquid Volume 56.0 mL 4.35 mL 23.7 mL 16.8 mL 76.0 mL 5.3 mL 32.0 mL 3.5 mL 47.0 mL Thermometers 68.0  -2.8  11.0  -1.1  28.1  16.0  8.0  -11.5  98.7  Answer to Worksheets

  37. Instruments around the room • Beaker • Buret • Volumetric Flask • Graduated cylinder • Scale • Erlenmeyer Flask • Thermometer

  38. Homework • Look through your textbook. Find 10 pictures that show a piece of chemical equipment being used. Name the page, the piece of equipment and describe how it is being used.

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