1. Burette = (Am.) buret ; a graduated vertical glass tube used to deliver variable volumes of liquid or gas ; usually equipped with a stopcock to control the liquid flow. Buret reading tips : Read the bottom of the concave meniscus You should always estimate the reading of any scale to the nearest tenth of a division. Avoid parallax ( 視差 ) Account for the thickness of the marking lines in your readings thickness of marking line = ca. 0.02 mL/ 50 mL buret volume of a drop = ca. 0.05 mL / 50 mL buret drainage rate = no more than 20 mL/min Washing any glassware with a new solution is a good idea. The air bubble often trapped beneath the stopcock of a buret should be expelled before use. The mass titration by a syringe is more accurate.

2. (a)Glass bead valve (b)Teflon valve Geissler Burette

3. Glass buret. Digital titrator with plastic cartridge containing reagent solution is used for analyses in the field. Battery-operated electronic buret with digital readout delivers 0.01 mLincrements from a reagent bottle.

4. An air bubble trapped beneath the stopcock should be expelled before you use the buret. Operating a buret. 1.Wash buret with new solution. 2.Eliminate air bubble before use. 3.Drain liquid slowly. 4.Deliver fraction of a drop near end point. 5.Read bottom of concave meniscus. 6.Estimate reading to 1/10 of a division. 7.Avoid parallax. 8.Account for graduation thickness in readings.

5. Buret and meniscus

6. Buret with the meniscus. Estimate the reading of any scale to the nearest tenth of a division. 9.68 mL

7. Buret volume (mL) Smallest Graduation (mL) Tolerance (mL) 5 0.01  0.01 100.05 or 0.02  0.02 25 0.1  0.03 50 0.1  0.05 100 0.2  0.10 Tolerance of Class A buret

9. Recommended method for manipulation a buret stopcock. 뷰렛에 적정용액 취하기

11. Volumetric flask : mess flask : measuring flask ; A laboratory flask primarily intended for the preparation of definite, fixed volumes of solutions, and therefore calibrated for a single volume only. TC 20 o C = calibrated to contain the indicated volume at 20 o C E : eingu  TD 20 o C = calibrated to deliver the indicated volume at 20 o C A : ausgu  Soak already thoroughly cleaned glassware in 3~6 M HCl in a fume hood for >1hr, followed by many rinses with distilled water. Volumetric flask

12. Class A glass volumetric flasks with glass stopper or Teflon stopper. Class B polypropylene plastic volumetric flask for trace analysis. Short-form volumetric flask with Teflon-lined screw cap fits.

13. Flask capacity (mL) Tolerance (mL) 1  0.02 2 5 10  0.02 25  0.03 50  0.05 100  0.08 200  0.10 250  0.12 500  0.20 1000  0.30 2000  0.50 Tolerance of Class A volumetric flask

14. The Lab Notebook The lab notebook must. State what was done. State what was observed. Be understandable to someone else Report  Date  Weather  Temperature  Humidity  Pressure  Name  Coworker  Objectives, chemical equations  Methods and procedure / Instrumentation and reagents  Results and discussions AConclusion A Reference

16. Summary Lab safety Chemical balance / tare, capacity, sensitivity, vernier, buoyancy, weights, tolerance, electromagnetic restoring system Drying / constant mass, desiccator, desiccant, ignition Filtration / crucible, vacuum filtration, decantation, policeman, ashless filter paper, mother liquor Transfer pipet Buret / meniscus, parallax Volumetric flask / TD, TC Lab notebook

17. Q n A Thanks. Dong-Sun Lee / 분석화학연구실 (CAT-Lab) / SWU.