26

Avoiding cooling again after keeping it ( for non critical products ) at room temperature is mainly to prevent forgetting it was not cold all the time and that it may not last as long as expected. Taking food from the fridge, you may not remember after a week or two that it was outside longer than it should have been. It can violate the safety by growth of ...


22

You assume there is X lithium and all of it cost Y. And then there would be no lithium to mine. Thats not quite right. As you are ready to pay more, harder to get sources become profitable and become part of available reserves. Sea has almost unlimited amount of lithium, but it is about x5 as expensive to mine. The total lithium content of seawater is very ...


21

Answer here from a quality manager in the pharmaceutical field in Europe. Pharmaceutical companies are obliged to perform stability tests for their products according to the relevant pharmaceutical (GMP) agency in your market (FDA/EMA/etc) and the international agreed guidelines like ICH Q1A-F and the WHO). These tests are carried out in stability chambers ...


21

Thousands of different chemicals, previously spatial separated, are mixed together after thermal death of cells, and kept at high temperature to react well. Final taste will depend on original system, but will develop by way unpredictable theoretically from basic principles. The answer for a particular biological source requires detailed knowledge about ...


21

I believe it is cost. According to 1, food-grade stainless steel works well as a container for milk. However, the article also says that the wholesale cost of a 0.568 L (19.2 fluid ounce) glass milk bottle in Great Britain was 0.35 £ ($0.50) in 2020. By contrast, I searched a few wholesale sites, and the least expensive staineless steel water bottle I could ...


14

The decisive factor is the plant origin of honey. The major components ( reportedly by some beekeeper books of my passed away father ) have ratio glucose : fructose about 1:1 to 1:1.7. Glucose reportedly crystallizes more readily, triggering fructose crystallization as well. So honey closer to 1:1 ratio has stronger tendency to crystalize.(**) Aside of ...


14

The state of a compound, solid, liquid, or gaseous is a property which is unrelated to the property / strength of a Brønsted or Lewis acid of said compound. Thus, you can not infer from its physical appearance if an acid is safe enough to be touched by skin; it may be irritant / corrosive even in absence of water (e.g., p-TsOH as a solid acid, triflic acid ...


10

A concept that captures how effective a detergent is at doings its job is aptly called "detergency." As might be expected this is a complex property and difficult to describe unambiguously with a single parameter. Quoting Ref. 1 : Detergency is difficult to evaluate because it depends on a multitude of variables that in most cases are ...


9

Interesting question but keep in mind that it is normal to dislike a subject. You don't have to like chemistry. Many people loathe physics and mathematics. The world is not affected. I am sure your experience is limited to general chemistry and Oxtoby. In statistical terms, one cannot and should not trust a single sample (=experience). However, some of your ...


9

In short: This is possible because «paper money» actually is not referring to the paper like paper from the office supply for (your) desktop printer or xerox, but to cotton paper. Because of the cotton, if folded and forgotten in a pocket of your jeans close to $\pu{40 ^\circ{}C}$, they may physically survive a pass in the washing machine with a mild non-...


8

The $\pu{3.6-3.8 V}$ range is a good general choice, but it may be battery-specific. The particular voltage for 40% charge may differ for different cell technologies, e.g. various deviations of electrode materials and due to cell aging. The optimal storage conditions, as you mentioned, are more often expressed as charge/capacity % ratio. Usually, the optimal ...


8

I have calculated pressure in container one and that is p1 = 342817.92 Pa, and in container two p2 = 326979.2275 Pa. Then I have substracted this two values which gives me 15838.6925 Pa. After that I have divided this value with two, to figure out how much do I have to decrease pressure in container 1, and that gives me 7919.34625 Pa. You cannot generally ...


7

It looks like a brass ( a class of alloys, containing mostly copper and zinc, being golden-like ), which surface was covered by protective plating , possibly by chrome or nickel(*). It was probably worn out mechanically and/or by corrosion due acidic sweat. (*)Nickel plating could be worn out easier than hard and resistant chrome.


7

People turn apple cider all the way to apple cider vinegar, so during the process, there will be a time when the amount and ratio of ethanol and acetic acid are optimally balanced for making ethyl acetate - but it doesn't seem to happen. However, given enough time (and oxygen and bacteria), maybe different things happen. Interesting that the expired cider ...


7

Any steel container is going to quickly show wear and dents in it. If you use one thin enough to be cost and weight effective, even more so. Milk is one of those products that has to look clean and fresh on the shelf. A dented can isn't going to work well in this situation.


7

Soapiness or anything like that cannot be represented by a single number. Hence no point in inventing such a quantity. Just like we cannot associate a plain number to odors, soapiness is scientifically meaningless because it will be an umbrella term. Just like the term polarity is misused, soapiness could be even worse. The only common property of ...


7

Let me solve the first half of it for you, and see if this gives you enough background to solve the second half on your own: Natural gas is methane ($\ce{CH4} (g)$). The balanced chemical equation for the combustion of methane is: $$\ce{CH4 (g) + 2O2 (g) -> CO2 (g) + 2H2O (g)}$$ We know it's balanced because the total number of atoms of each element on ...


6

$\ce{C4O5}$ can be found in a Chinese patent art(Ref. 1). It is called Oxolane-2,3,4,5-tetrone both in the patent and PubChem. In the patent, $\ce{C4O5}$ is shown as compound 2 and appears to be a compound which undergoes further reaction with itself eventually giving a desired product. A google translation of the relative portion of the patent, from ...


6

At very dilute concentrations, the solvating power of water overcomes the natural tendency of surfactant molecules to agglomerate into a separate phase. The shear numerical excess of water molecules just about totally dissociates the bulk surfactant and dissolves it as separate molecules. So a mixture of surfactant and water can be a true solution - clear ...


6

So it finally turned out to be an artefact, sorry. The probe was protected by a small metallic tube. Somehow water condensed inside. Since this water is isolated from the main liquid, it performed its own phase-transition releasing its latent heat right next to the sensor. The effect was not appreciated when freezing the probe alone. I don't know why, maybe ...


5

Unfortunately this is not feasible Current catalytic converters are designed to remove noxious pollutants from exhausts. Things like carbon monoxide (poisonous) and nitrogen oxides (noxious and irritating). The trouble with doing this for carbon dioxide is fundamental. Carbon dioxide and water are the ultimate products of combustion of hydrocarbons because ...


5

Chalk cannot at given conditions explode chemically, spontaneously turning into other compounds. It could locally "explode" mechanically as consequence of mechanical stress caused by thermal dilation due changes to temperature. But calling it explosion would be very much exaggerated. It would be rather just cracking. There is a way such cracking ...


5

I think this is an optical phenomenon and no chemical reaction is taking place. When you are looking at a solution, you are basically perceiving its absorption spectrum. When you have a solid, you are looking at the reflectance spectrum and the story is more complex, if you have a heterogeneous solid like this stuff. If you originally had the solution and ...


4

A1: There is no displacement of the wall, forces are in equilibrium with zero net force. There are initiated stronger vibrations on warmer wall side by energetic hot air molecules. And weaker vibrations on colder wall side by energy leaching cold water molecules . A2a: If the wall initial temperature was the cold water temperature, then yes. Otherwise no, as ...


4

Generally, many dyes, natural or artificial, change color with changing pH ( acidity ). Natural anthocyan dyes are usually about red in acidic, about blue/violet in alkaline solutions. You can e.g. check red beetroot juice when washing soda is added. So that clear solution was probably an alkaline solution. These reactions are reversible, if pH is returned ...


4

A more plausible explanation is that it is not water that is boiling. The "organic substances" and maybe the "nitrogenous substances" in the juice could include some more volatile components that may pass selectively into the gas phase at a lower temperature than most of the solution. Such a vapor would not be the pure organic or ...


4

Baking soda is sodium bicarbonate NaHCO$_3$. It is stable in air indefinitely. Baking powder is a mix of sodium bicarbonate and a powdered acid, typically an aluminum or calcium hydrogen phosphate, which, in the absence of moisture, is stable for a long time (maybe a year? maybe more). After exposure to moisture, it will release CO$_2$ and become inactivated....


4

Note that all salts, used in humidity calibration, dissociate to their respective hydrated cations and anions when dissolved. From the solution crystallizes the sesquihydrate $\ce{K2CO3·​\frac 32 H2O}$ ("potash hydrate"). Heating this solid above 200 °C gives the anhydrous salt (Wikipedia). It seems you have anhydrous carbonate, that hydrates ...


4

Most likely this was an artificial "lake" sample and someone gave you distilled water instead. Making artificial water samples is not an unusual practice in teaching laboratories. Natural water cannot have zero concentration of chloride ion. Sodium and chloride ions are very common contaminants even in pure reagents. There is no "zero" ...


4

Polyethylene-coated cartons are designed to be recyclable, and I suspect that the environmental impact of people who don't offer those for recycling is lower than the environmental impact of putting stainless steel into rubbish dumps. Glass is very recyclable, but there are additional transport costs associated with the weight and volume overheads of glass ...


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