Hanna 1ml is not really 1ml?

Notsolostfish

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It says add 1ml or reagant for calcium. I have a kitchen scale. I zerod it out add it 1ml. And its still 0. It didnt even touch the 1ml. Hows that test accurate? And how can we trust it with results for calcium?

 

Dan_P

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It says add 1ml or reagant for calcium. I have a kitchen scale. I zerod it out add it 1ml. And its still 0. It didnt even touch the 1ml. Hows that test accurate? And how can we trust it with results for calcium?


Your scale malfunctioned, your scale is less sensitive than 1 g or you added 1 mL of air.
 

BanZI29

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1ml is not a weight, it's a liquid volume measurement. depending on the liquid your using, it can have a different density and therefore weigh more or less than another liquid. you need to use a syringe to measure liquid volume
Also, that scale may not be as sensitive as you want. try it again and zero it with the bottle on.
 

PotatoPig

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The problem is the scale isn’t precise enough.

If you’re using a scale to measure about 1gram (assuming the solute is water) it needs a precision of at least 0.1g, even then you have an inherent minimum +/-5% error. Ideally the precision would go to 0.01g or better for measuring such a small weight.
 

Gtinnel

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A kitchen scale is not going to be accurate enough to read 1ml. Also, as already mentioned a ml is a measurement of volume not weight, so your scale is assuming a volume based upon the density of a specific liquid (I would assume water).
When measuring weight the last digit is never accurate anyway. As an example your scale says 0ml so if you trust it then you have not added anything to the vial.

ETA
beating a dead horse wtf GIF
 

Mhamilton0911

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#1, The kitchen scale simply isn't sensitive enough to register such a small amount,
And #2, ml is a volume measurement, not a weight. So although a more sensitive scale will show you the weight of 1ml of liquid, that's not how to measure out a volume of liquid. Use a dosing syringe from a farm store or a medical grade one.
 

KrisReef

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Definition 1ml (pure water) = 1gram

Hanna Calcium uses 1ml of seawater which should weight a fraction more than pure water.
 

BanZI29

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So not to get all high school science teacher on ya but, all liquids will have different densities depending on what it is or is in it. this is why you should not weigh out liquids, especislly for water tests. Always measure in liquid volume.
 

KrisReef

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.025g more even. Don’t ask me to convert that to millimeters though. :zany-face:
It’s a difficult conversion but the correct answer is almost always 1. (Unless you’re using heavy water instead of RODI.). Then relativity takes hold and physics calculations must be performed to take into account particle deterioration rates, not to mention evaporation at STP. According to Einstein it’s really easy but I blindly trust Hanna and pray that my syringe is properly calibrated.
 

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