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Author: Subject: Best way to measure a milliliter?
Yttrium2
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[*] posted on 30-9-2022 at 15:54
Best way to measure a milliliter?


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j_sum1
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[*] posted on 30-9-2022 at 17:03


A micropipette. Biologists do it all the time.

Using what I have in my lab -- a Pasteur pipette, a lot of time calibrating it, and being prepared to suffer 10% inaccuracy.
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[*] posted on 30-9-2022 at 18:23


Best as in most accurate? or most efficient? I thought there was going to be more to this than the title suggests.

I was going to suggest a set of scales weighed out to 1g(AFAIK that uses to be the global standard or something)
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[*] posted on 30-9-2022 at 19:01


20 drops to one ml.....solo




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[*] posted on 30-9-2022 at 19:37


In addition to j_sum suggestion - glass bulbe pipette.
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[*] posted on 30-9-2022 at 20:12


Checked in to say I misread. I thought you said microlitre.

A standard burette or 10mL cylinder will give you a mL to within 0.1mL or better.
You can buy volumetric pippettes that give a mL. (Although my smallest is 2mL.)
There are graduated pipettes available. They look like glass tubes with markings. I have several that measure up to a mL in 0.01mL increments.
You can measure the density of your liquid. Easiest method would be to weigh a known volume from a volumetric pipette. Then you can use a digital scale to get the required amount.
You could dilute. For example, 25mL made up to a litre. Then you measure out 40mL of your chemical with reasonable accuracy.

The method that works best for you will depend on equipment available and the accuracy needed. I can't think of a home lab situation where none of these would work.
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Yttrium2
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[*] posted on 30-9-2022 at 21:45


J_sum1 said….


“ You could dilute. For example, 25mL made up to a litre. Then you measure out 40mL of your chemical with reasonable accuracy.”


This part totally slides me.



Thinking of taking you advice on getting a math book, or collection of them.
Along with a printer! Taking notes takes a while and is sloppy, sometimes.?
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[*] posted on 30-9-2022 at 21:57


25mL to a litre is a dilution of 40x.

So, instead of measuring out 1 mL of your undiluted reagent, you measure out 40mL of your solution for the same quantity if chemical.

40mL is easier to measure accurately than 1mL with most common amatuer lab gear.
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[*] posted on 30-9-2022 at 23:35


Quote: Originally posted by solo  
20 drops to one ml.....solo



20 drops of water in 1 ml, but that's not necessarily true for other solvents, like Ethanol. See Drops in millilter


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[*] posted on 1-10-2022 at 07:45


There is some analytical glass that you can use for precise measurement like mentioned before pipette or burette. I would personally go with pipette as it is generally easier to use than burette and you will waste less reagent.

if you have an analytical scale and pycnometer you may precisely measure the density and instead trying to measure the volume you can use weight which will be much more precise than volume-based measurement. But you would need to have a good scale for that.

If you can dilute the solution to lower concentration you will be able to measure it even easier and with much greater accuracy.
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Fulmen
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[*] posted on 1-10-2022 at 08:53


For dilute aqueous solutions (and any reasonably pure liquid with a known density) you can use weight.



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[*] posted on 1-10-2022 at 09:04


Quote: Originally posted by Fulmen  
For dilute aqueous solutions (and any reasonably pure liquid with a known density) you can use weight.


Volatile liquids like DCM or MeOH are hard to weigh precisely.

[Edited on 1-10-2022 by Bedlasky]
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Fulmen
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[*] posted on 1-10-2022 at 09:12


That's true, unless you can add it directly to another liquid (or absorbent) that will reduce evaporation. But volatile liquids are hard to measure by volume as well. Not only due to the vapor pressure, the surface tension will also be wrong for most pipettes.



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[*] posted on 2-10-2022 at 06:44


A 1ml syringe made from PE?

syringe.jpg - 120kB




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[*] posted on 5-10-2022 at 15:34


If you know what your liquid is and if its pure, use density value, a good jewelers scale and math to get a quite precise milliliter.
Or use a good volumetric pipette.
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