39

The $\mathrm{pH}$ of pure water (rain as well as distilled water) in equilibrium with the atmosphere ($p_{\ce{CO2}}= 10^{-3.5}\ \mathrm{atm}$) can be calculated as follows. $$[\ce{H2CO3^*}]=K_\mathrm H\cdot p_{\ce{CO2}}$$ where $[\ce{H2CO3^*}]$ is the total analytical concentration of dissolved $\ce{CO2}$, i.e. $[\ce{H2CO3^*}]=[\ce{CO2(aq)}]+[\ce{H2CO3}]$, ...


24

Measure the change in mass over time of the remaining liquid. Though some water will also evaporate, you can control for that by keeping the humidity near 100%. If you have to be precise, collect the outgassed $\ce{CO2}$ in a liquid-nitrogen cold trap. Check the mass of the condensate, which should equal that lost from the soda. Check purity, to be really ...


21

Yes, you can use a common stove to test for cations. But a stove is designed to minimize the risk of incomplete combustion (which could lead to production of carbon monoxide), hence its flame always appears as an intense blue flame. Such color contamination could be problematic when testing for cations. In contrast, the combustion (and the color of the flame)...


20

Honey is indeed a complex mixture containing more than hundred compounds. As for Wikipedia and depending on the point of view it is a supersatured liquid solution a viscous supercooled liquid (in the sense that it can get so viscous as to appear solid, without affecting its status of being a supersatured solution, and undergoes glass transition). https://...


16

Melting and dissolving are all the same when you look at mixtures close to saturation. You can say water lowers the melting point of the sugar, or that the solubility of sugar increases with temperature. Different description, same fact. What makes this seem different from e.g. a salt water solution is that the molten (i.e. non-crystalline) sugar is fully ...


16

You are forgetting an important component of the air: carbon dioxide. When it dissolves in pure water (=rain water), it makes it acidic. It is not considered that harmful. Acid rain has a negative connotation; it is mainly caused by anthropogenic activities. The low pH of acid rain is due to sulfur oxides and nitrogen oxides and it is indeed below 5.7. ...


15

Foam is a side effect of using a tensio-active agents (though some tensio-active agents are engineered to produce as little foam as possible, e.g. in washing machines). In fact, you could consider that, if soap has nothing better to do, it will form foam. This answers some of your questions: foam does not (really) carry away dirt and its percentage of ...


15

According to [1, pp. 281–282], solution of sodium chloride $\ce{NaCl}$ prepared by dissolving 25 g of salt in 100 g of water has boiling point of 104.6 °C. Additional data is available in the following table for the aqueous solutions of common salts and bases. English transcription; column 1: Compound; columns 2–6: Concentration, g/100 g water — boiling ...


13

Measure concentration in a fixed volume of air Easiest way might be to put it in a sealed impermeable bag or box and measure the CO2 concentration over time. Home hobbyists use something like the MG-811 CO2 sensor or a simple non-dispersive optical sensor and connect it to a Raspberry Pi or Arduino using an analog to digital converter chip (ADC). For (a ...


10

Generally, improvement of measurement process has much better positive impact on results, than sophisticated mathematical processing of low quality data. But, sometimes we are forced to data what we have. There are 3 quantities: resolution = the smallest difference of directly measured value, distinguishable by the tool, precision = Level of uncertainty ...


9

The spontaneous emission of light by a substance not resulting from heat is luminescence (a type of cold-body radiation). $\ce{^1}$ A few types of luminescence are: Bioluminescence: Made by living creatures such as fireflies, glow-worms, and many marine creatures. Chemoluminescence: made by a chemical reaction. Glow sticks work this way. ...


9

Under atmospheric pressure, dissolved carbon dioxide can reach an equilibrium state in water that yields a pH of as low as 5.7


7

The vapour tension over the saturated table salt solution { the best with the solid salt excess) is equivalent to the relative humidity about 75 %. If the rel. humidity is lower than 75%, the solution evaporates and the salt crystallizes. If the rel. humidity is higher than 75%, the solution absorbs the air moisture and the salt is dissolving. Such ...


7

Your non-trivial question has a yes and a no. It is not possible to increase the accuracy of a dataset just by mathematical means. If you knew the systematic error in your data then you can do the arithmetic to correct the error. There is no a priori way to ascertain if your measurement tool lacks accuracy until and unless we have a reference for comparison. ...


6

In nature fat is stored as triglycerides (TGs): Three fatty acid (FA) chains bound together by a glycerol backbone. Olive oil is mainly composed of TGs, though it also contains small amounts of free fatty acids (FFAs). An example of Triglyceride (from Wikipedia) Soap is commonly made via the reaction of triglycerides with a strong base: usually Sodium ...


6

The name 'formic acid' has been derived from the name 'formica' as it is derived literally from ants. Wikipedia clearly states: The word "formic" comes from the Latin word for ant, formica, referring to its early isolation by the distillation of ant bodies. If you type 'formic acid etymology' in Google, it will give two links that proves the above ...


6

For a direct measurement of $\ce{CO2}$ content, it is possible to use infrared (IR) spectroscopy. Infrared radiation can be absorbed by molecules, causing them to vibrate. The exact frequency of the radiation absorbed is often characteristic of certain bonds or functional groups. In particular, the fundamental antisymmetric stretching mode of $\ce{CO2}$ in ...


5

Yes , a quick and cheap way to reduce chlorine residual is to add ascorbic acid (VITAMIN C), which if added in an equal molar amount to free chlorine would completely eliminate chlorine residual within 1 min. I am quoting from ABSTRACT from a paper from, Int. Journal of Engineering Research and Applications , ISSN : 2248-9622, Vol. 3, Issue 5, Sep-Oct ...


5

As mentioned in the comments, this topic can become exceedingly complex if all the aspects of current-gen photochromic lenses are brought to the table (and I'm sure a lot of it is locked away in trade secrets). My goal here is to provide some insight into the chemical/physical mechanisms at work. Photochromic sunglasses are a smart new application of very ...


5

You don't have to reinvent the wheel. Food industry already uses quite simple oxygen scavengers for decades, and one of the most affordable formulations include iron powder mixed with sodium chloride. Typically, an oxygen scavenger is packaged in small packets (sometimes labeled as "oxygen absorber" or "antioxidant") that are added with the product inside ...


5

Better than a hydrometer, use an Abbe refractometer to measure the index of refraction, which varies with sugar concentration. It requires just a drop of liquid, and that small sample is unlikely to have bubbles, reducing density. You can make a refractometer to measure the sugar concentration, or you can buy one for ~$US20. That said, diet sodas have been ...


5

Vitamin E acetate, or α-tocopheryl acetate, exists in two forms: D-form (solid/highly viscous at 20 °C) and a racemate (viscous liquid at 20 °C). Interestingly enough, the difference in physical properties is well denoted in German Wikipedia article, whereas English Wikipedia omits this. Also, I noticed many authoritative sources arbitrarily listing a ...


4

It's not that complicated of an answer. developer to bring out the image As I'm sure you know photographic film is coated in light-sensitive material (usually silver bromide). The thing is for black and white silver halide films, that the light does not react that intensely with the film, only a very few silver atoms get reduced. During development ...


4

Many of the components of gasoline (petrol) have notable odours A simple starting point for understanding the odour of gasoline is the typical composition of the product. That composition varies a lot and always has done as different refineries use different processing techniques and different crude oil sources have different components to start with. And ...


4

I wasn't sure what other conditions you needed for your salt bath, yet I listed few for your convenience together with the salt bath of $\ce{KNO3/NaNO2}$ (bath 5) for comparison: $$ \begin{array}{ccc} \text{Bath#} &\text{Composition} & \text{Approx. melting poing} & \text{Working temp. range} \\\hline 1 & \ce{NaCl}, \ce{KCl}, \ce{BaCl2}, \ce{...


4

Water contains negligible amount of $\ce{CaCO3}$ or $\ce{MgCO3}$, as these are almost insoluble in water. What you are interested in are bicarbonates $\ce{Ca(HCO3)2 + Mg(HCO3)2}$. Their content is known as the temporary or carbonate water hardness that can be expressed as $\ce{CaCO3}$ equivalent. The complement to the carbonate hardness is the permanent ...


4

What is this process called exactly? As far as I understand "deliquescence" is a property and not a process. Does the exchange of water between my pile of salt and the air have a specific terminology? Something that would go along with terms like evaporation, sublimation, condensation, etc.? Perhaps some mash-up of adsorption and dissolution? The ...


4

Unfortunately calcium sulphate, gypsum, $\ce{CaSO4}$, is depressingly stable and nothing non-deadly will dissolve it. The other posts you have seen are about calcium carbonate, chalk/limestone/marble, $\ce{CaCO3}$, which acids will dissolve, although people do not in practice use that fact to make holes in it. One of the first difficulties would be to get ...


4

You should not regard this answer as medical advice. If concerned about your health consult a physician. The glue you link to (TAMIYA EXTRA-THIN CEMENT, made by IKEGAMI PAINT INDUSTRY COMPANY), according to a material safety data sheet (MSDS) I was able to retrieve online, appears to be a 1:1 mixture of acetone and butyl acetate. Such a mixture works in a ...


4

The part of the windshield that you are talking about is called the frit. This is typically made up of some form of high-heat enamel, and as far as I was able to find, it is intended to increase the surface roughness of the inside of the glass to increase the ability for the adhesive to stick to it. I was not able to find any specific mention for what type ...


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