at 25 C, 95% ethanol has an SG of 0.79991, and 100% ethanol has an SG of 0.78506. that's not a very big difference, so just want to see if anyone else
has had success with this.
i bet you could also use this to check the concentration of sulfuric acid? seems it would be very useful in the home lab.
I'm getting into esters. Just yesterday i made some methyl salicylate by following nile red's video, and that was really fun, it smells like root
beer. i also want to try out ethyl salicylate, isopropyl salicylate, and butyl salicylate. so it is important to invest in equipment for making
alcohols anhydrous, and sulfuric acid as concentrated as possible. Don't just want an ethanol hydrometer for brewing, because I also plan to make
anhydrous isopropyl alcohol.
[Edited on 4-12-2019 by Cou]Sulaiman - 3-12-2019 at 19:53
Would this specific gravity hydrometer be precise enough to tell if 190 proof ethanol has been made anhydrous?
NO
1) There is no indication of the accuracy or calibration or temperature that it is calibrated for
2) Can you reliably read the scale to tell the difference between 99%=0.78814 and 100%=0.78506 (at 25oC) ?
YES - If you very carefully calibrate the hydrometer yourself you should be able to tell the difference between 99% and 100% ABV
but NO ... some reactions require much less than 1% water to be present, so 99.5% ABV would not be considered as anhydrous.
You would also require a thermometer accurate to about +/-1oC to have reasonable confidence.
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For ethanol:water I use a cheap Chinese kit that so far seems reliable and accurate
e.g. https://www.amazon.com/0-100-Hydrometer-Alcoholmeter-Alcohol...
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IF you have digital scales and at least one calibration weight then I suggest that you buy a volumetric flask,
e.g. https://www.amazon.com/Volumetric-Ground-Stopper-Karter-Scie...
This would allow more reliable measurements
and also be generally useful for making up various solutions of known w/w%, w/100ml, molarity etc..
Before you buy a volumetric flask be sure that it is suitable for the range of your scales,
e.g. the flask that I pointed to weighs about 100g, with 100ml water it would weigh about 200g,
with 100ml az. sulphuric acid it would weigh about 284g,
so you would probably need 0 - 300 g scales ... etc.
You would also need an accurate (of self-calibrated) thermometer.
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If you do not have suitable scales/balance then get one !
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Use your scales, calibration weight, thermometer and volumetric flask to measure the density of distilled water,
the result will indicate your future expected levels of accuracy,
of your equipment and proficiency.
Using typical cheap eBay 0-300g x 0.01g scales with a cheap calibration weight, thermometer and the flask pointed to above,
I would be content with <= 0.2% error,
< 0.1% error consistently (e.g. three consecutive times) would be exceptional wg48temp9 - 3-12-2019 at 20:09
The hydrometer the OP picked is about the worst one you could find for its resolution.
The resolution of a hydrometer is determined by the length of the scale and the ratio of the bulb volume (the part below the scale) to that of the
volume of the part that contains the scale. You need a thin stem and large bulb for good resolution. It also needs to be calibrated accurately.
Typical lab hydrometers have large bulbs relative to the stem that can have full scale range of 0.1 or 0.2SG and can be read to 0.001 SG.
forget this thread, i just decided to get a regular ethanol hydrometer for now, since dudadiesel sells 99% isopropyl alcohol and ethanol is the only
alcohol i need to dryrockyit98 - 4-12-2019 at 05:39
buy a gravity bottle aka Pycnometer for more accurate measurements. http://www.sciencemadness.org/smwiki/index.php/Pycnometer i use 5ml one with 50.000g scale with a thermometer for more accurate readings.Cou - 4-12-2019 at 10:06
I just woke up from a nightmare where someone replied to this post with "No, don't worry about these kinds of posts, they make us feel better for not
being idiots!" xD
