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If I were to Calibrate a Graduated Cylinder

  1. Feb 3, 2010 #1
    If I were to calibrate a graduated cylinder, I would;

    1. Guesstimate the 50ml mark for a graduated cylinder & fill with water of a known temperature.

    2. Drain the water out & weigh it, If you weigh it in a seperate container you must know the weight of the seperate container first & subtract this from the final result.

    3. Using the formula [mass=weight/gravity] we find the waters mass & then use

    [volume = Density/mass] - density being known as a function of temperature - to find out how

    close the volume was to 50ml.

    4. Repeat, adding or removing water of the same temperature until you've arrived at 50ml.



    Of course there are easier methods but this is one possible way of getting a reasonably accurate graduated cylinder, right?




    :biggrin: Gracias :biggrin:
     
  2. jcsd
  3. Feb 3, 2010 #2

    berkeman

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    Dont' use a 2nd cylinder....
     
  4. Feb 3, 2010 #3

    Gokul43201

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    Step 4 would be unnecessary if you actually filled exactly to the 50ml mark in step 1.
     
  5. Feb 4, 2010 #4

    turbo

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    Put the un-marked cylinder on a scale and tare it. Add room-temperature water until the scale reads 50g. Scribe at the meniscus level. Done.
     
  6. Feb 4, 2010 #5

    chemisttree

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    This will give you a calibration known as 'To Contain" or TC. If you want to use it to deliver 50 mL you will need the second vessel. That calibration would give you something known as a "To Deliver" or TD calibration. Every grad cyl I have ever used is of the TC type.
     
  7. Feb 4, 2010 #6

    Gokul43201

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    Why is that? No one performs a reaction in a grad cyl. Wouldn't it make more sense for labs to stock TD calibrated grad cylinders if you're going to pour the stuff out? Or is it that it rarely makes enough of a difference to matter?
     
  8. Feb 5, 2010 #7

    chemisttree

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    Yes, Gokul. All your precise work in making up standard solutions are made up using precise balances for solids and volumetric pipettes of some type of the TD type. Volumetric vessels are invariably used as TC since they are designed to be added to until a certain volume is attained. The resulting solution is precise but no one would ever use one of those volumetric flasks or grad cyls to accurately deliver known volumes. In cases where they are used to measure reagents or solvents, they are exact enough for the purpose at hand, of course.
     
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