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Author: Subject: The Short Questions Thread (4)
j_sum1
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[*] posted on 23-11-2019 at 19:31


My hardware store hydrochloric acid seems to be contaminated with Ti (of all things).
It gives a pale purple / lilac cloudy hue when reacting with zinc or magnesium.
It forms a bright orange complex with a very small of dilute peroxide.

Or is there something else that would give this same set of results?
How would titanium contamination even happen?
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Morgan
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[*] posted on 4-12-2019 at 11:29
Decibel meters


Any thoughts on buying a decibel meter, what weaknesses or drawbacks come into play or best buy on eBay? There're some for 15 dollars or so supposedly very accurate.
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[*] posted on 4-12-2019 at 15:13


Commercial decibel meters have (or did have in my time) selectable weighting curves and most importantly, they were calibrated.
Calibrated equipment allows 'legal' measurements (in my case noise levels in train cabins),
a cheap or diy sound level meter could be technically as good or even superior,
but it would not be acceptable for commercial monitoring purposes.

A sound level meter is a fairly simple device,
it is the calibration that is important.




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[*] posted on 4-12-2019 at 15:20


Quote: Originally posted by Morgan  
Any thoughts on buying a decibel meter, what weaknesses or drawbacks come into play or best buy on eBay? There're some for 15 dollars or so supposedly very accurate.
If you've a half decent smartphone, look for any number of free apps which use your phone's hardware to act as a decibel meter.

Some of them seem to work pretty well.
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[*] posted on 5-12-2019 at 10:37


Thanks for those thoughts all. I was reading some of the complexities of measuring sound on Wiki. This was interesting too.

"However, the reading from a sound level meter does not correlate well to human-perceived loudness, which is better measured by a loudness meter. Specific loudness is a compressive nonlinearity and varies at certain levels and at certain frequencies.These metrics can also be calculated in a number of different ways."
https://en.wikipedia.org/wiki/Sound_level_meter
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Sulaiman
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[*] posted on 5-12-2019 at 19:27


Accoustics and auditory perception is a complex area,
accoustics and especially sonar were the key topics of some of my lecturers and their post-grad researchers,
about 30 years ago I was designing, building and selling (small private sales) 'Hi-Fi' equipment,
one of the important areas is perceived loudness
https://en.wikipedia.org/wiki/Equal-loudness_contour
but the most complex is Psychoacoustics
https://en.wikipedia.org/wiki/Psychoacoustics
(I can discuss this topic ad nauseum)

What is the intended use for the sound level meter ?




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[*] posted on 6-12-2019 at 10:56


I wanted to know the level of sound some of my smallish jam jar jets make with exhaust tubes attached which increases the robustness enough so that I wear hearing protection - just hot gases going in and out a single orifice somewhat fast.

This sort of thing as an example.
https://www.youtube.com/watch?v=T-EoSOfaplo
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[*] posted on 9-1-2020 at 01:32


Quote: Originally posted by j_sum1  
My hardware store hydrochloric acid seems to be contaminated with Ti (of all things).
It gives a pale purple / lilac cloudy hue when reacting with zinc or magnesium.
It forms a bright orange complex with a very small of dilute peroxide.

Or is there something else that would give this same set of results?
How would titanium contamination even happen?


Bumping this since the exact same question with the same product has come up with another user. I think Ti is the most likely culprit: nothing else I know fits the symptoms. But how would Ti have gotten in there? Seems a mystery.
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[*] posted on 9-1-2020 at 01:57
sodium bichloride (say what?)


My latest project has been installing a small swimming pool. It is filling as I type. (Yay! Relief from the aussie heat!)
It comes with a couple of manuals that appear to have been kludged together from a range of models and passed through at least one poor translation process. It is a bit unclear to say the least.
When it comes to the section(s) on chemicals to maintain correct water chemistry, there is a mountain of conflicting and contradictory information. It mentions sodium dichloroisocyanuric acid. It also mentions bromine in one place. It has an ozone generator and so mentions that. It recommends monopersulfate. But the bulk of the instruction centres around "sodium bichloride". I am wondering what on earth is meant by that.

Any insights? It is clearly an inappropriate name for something. But what? Does anyone know of any pool chemicals that are commonly misnamed as sodium bichloride?
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[*] posted on 9-1-2020 at 02:57


The only one I can think of is sodium hypochlorite. Where I live, we can buy big jugs (10 liters, or even 20 liters) of 12.5% active chlorine (solution of NaOCl in water). This is poured in a swimming pool for chlorinating purposes. Sometimes it is combined with cyanuric acid in order to stabilize the chlorine. This is important for outdoors swimming pools in full sunshine, which otherwise suffer from rapid decomposition of the hypochlorite to chloride and oxygen by UV-light.



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[*] posted on 9-1-2020 at 04:38


Maybe they meant sodium bisulfate, which is a common pH-down pool chemical?
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[*] posted on 9-1-2020 at 08:32


Quote: Originally posted by j_sum1  
My latest project has been installing a small swimming pool. It is filling as I type. (Yay! Relief from the aussie heat!)
It comes with a couple of manuals that appear to have been kludged together from a range of models and passed through at least one poor translation process. It is a bit unclear to say the least.
When it comes to the section(s) on chemicals to maintain correct water chemistry, there is a mountain of conflicting and contradictory information. It mentions sodium dichloroisocyanuric acid. It also mentions bromine in one place. It has an ozone generator and so mentions that. It recommends monopersulfate. But the bulk of the instruction centres around "sodium bichloride". I am wondering what on earth is meant by that.

Any insights? It is clearly an inappropriate name for something. But what? Does anyone know of any pool chemicals that are commonly misnamed as sodium bichloride?


Perhaps if you gave more context by posting the relevant section of the instructions it may be obvious what chemical they are referring to.

If the instructions are unclear and conflicting why not ignore them. There is lots of info on the web about maintaining the chemistry of a swimming pool. I would think if you are going to use the ozone generator you will have to pick a chemistry that's compatible with that.




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[*] posted on 9-1-2020 at 14:12


Clearest statement anywhere in the manual:
Quote:
We recommend using chlorine particles of sodium bichloride for water disinfection, because sodium bichloride can be completely and rapidly dissolved in water and its PH value is close to neutral.

The most likely candidate would be Na-DCCA. Sodium salt with two chlorines so the name fits. Soluble solid with little affect on pH.

You are correct: I am not going to rely on the manual since it is so unclear. But it was important to read anyway. I do need to select a treatment process compatible with materials used in the pool. I have read a few online guides as well. I am happy with the chemical theory. I am not happy with some of the terminology and descriptions given. And I am trying to get my head around quantities. All the guides refer to "total alkalinity" measured in ppm as separate from pH. I would much prefer molar concentration of carbonate if that is what is meant. I have read some truly shocking descriptions of chemical equilibrium. Fortunately there is some good information amidst all the crap out there.
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[*] posted on 9-1-2020 at 14:37


The Mandarin to English translator strikes again

*edit* pulled some generic acetaminophen by refluxing the pills in acetone. The damn stuff xtallized this weird reddish color. Any thoughts?



IMG_20200109_164103.jpg - 987kB

[Edited on 1-9-2020 by arkoma]




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[*] posted on 9-1-2020 at 18:46


Did you use pills that may have contained a red dye? Perhaps the dye was adsorbed on the crystals. You could try treating your acetone solution with activated carbon to remove the dye before the crystallization step. Also, washing the crystals on the filter with acetone may remove the dye, assuming that it is adsorbed onto the crystals of product.
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[*] posted on 22-1-2020 at 16:12


Does anyone know where I can get a datasheet for a R450 photo multiplier tube.

TIA,
Yob
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[*] posted on 26-1-2020 at 11:07


Can sodium sulfate be used instead of potassium sulfate to precipitate neodymium and iron as a double sulfate salt?
Thanks




List of materials made by ScienceMadness.org users:
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