Error N Obeidi The Kind of Error Random
Error N. Obeidi
The Kind of Error • Random Error • Systematic Error
Random Error • Random • Unpredictable • Independent on: 1. Temperature 2. Voltage 3. Equipments 4. ……
Systematic Error 1. Constant Error 2. Proportional Error
Glassware
Glassware • Container And Receiver • Volumetric Glassware 7
Container And Receiver • • • Beaker Erlenmeyer Flask Test Tube Reagent Bottle Photometry Cuvettes 8
Volumetric Glassware • Volumetric flask • Graduated Measuring Cylinder • Pipette
Various Pipettes 11
Pipetting technique 12
No 1 2 3 4 5 6 7 8 9 10 volume 4. 93 9. 54 14. 21 19. 10 24. 03 28. 91 33. 80 38. 64 43. 50 48. 27
ﻭﺯﻥ ﺣﺠﻢ w f – w v Delivered volume گﺮﻡ 2 = ( ﻭﺯﻥ ﻇﺮﻑ ﺗﻮﺯیﻦ w v ) 1 2 0. 01886 1. 0034= ﺩﺭﺟﻪ 25 ( ﺩﺭ ﺗﻬﺮﺍﻥ ﻭ ﺩﻣﺎی f t) 3 4 0. 02258 Delivered volume = (w f – w v ) * f t 0. 02047 5 6 7 0. 01886 SD= √(x-x‾)² =0. 012 n CV= SD Χ 100=0. 012 x 100=6. 2 % 8 9 0. 01866 10 0. 01896 0. 01886 0. 01967 x‾ 0. 0195
(expected val. ) =0. 427 ﺟﺬﺏ ﻧﻮﺭی ﺩﺭﺑﺎﻟﻦ ژﻮژﻪ (obs. val. ) x‾ =0. 481 ﻣیﺎﻧگیﻦ ﺟﺬﺏ ﻧﻮﺭی ﺩﺭ ﻟﻮﻟﻪ ﻫﺎ SD=0. 00493 CV% = 1. 02 Bias%=(0. 481 -0. 427)/0. 427 * 100=3. 88 0. 475 0. 481 0. 478 0. 474 0. 491 0. 482 0. 479 0. 485 0. 483 0. 481 1 2 3 4 5 6 7 8 9 10
Required Tolerance for Volumetric Glassware Capacity, m. L Pipetts Class A or Equiv. TD 1 10 25 100 200 ± 0. 006 0. 02 0. 03 0. 08 0. 10 Graduated Volumetric Flasks Cylinder (Class A) TD TC ± 0. 1 0. 3 0. 6 1. 4 ± 0. 01 0. 02 0. 03 0. 08 0. 10 23
Cleaning Of Glassware • Rinse with tap water • Soak in water with small amount of detergent for at least 1 hour • Use a cleaning brush • Rinse with tap water • Rinse with deionized water 3 -5 times • Dry in a hot oven ( <100 C) or RT • Check glassware for cleanliness randomly 24
Plastic ware/Types • Polyethylene , Polypropylene • Polyolefin • Polycarbonate • Teflon 25
Advantages/Disadvantages • Unbreakable • Not release ions • Bind various solutes • Polyethylene permeable to water • Binding to dyes, iodine , picric acid 26
Cleaning Of Plastic ware • Like glassware • Some of them are not autoclavable 27
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