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# Tag Info

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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. $[\ce{H2CO3^*}]=[\ce{CO2(aq)}]+[\ce{H2CO3}]$, ...

32

It is not proven that "sugar makes your body acidic"! Your body's pH is very tightly regulated by the body's internal systems; it is also different in different parts of the body - the stomach is acidic (1.0-2.5), the intestine are mildly basic (jejunem 7-9) terminal ileum 7.5 reference here. Blood pH is 7.35, and any deviation from this is indicative of ...

22

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://...

21

Smell works because your nose detects substances in the air. Everything you can smell is the result of a molecule carried by air interacting with complex proteins in the nose/mouth (smell and taste are related but taste copes with solids and liquids as well as volatile airborne stuff). We broadly understand how smell works but the exact details are often a ...

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)...

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

I believe the ice cracked due to residual strains from freezing. Since ice freezes from the outside inward and it expands as it freezes, that as the inner water freezes, it imparts a tensile force on the surrounding ice (like the opposite effect of tempering glass). As the warm liquid removes ice, the cross sectional area under tension decreases while the ...

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 ...

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

One place where sugar does cause acidity is your mouth. The bacteria living in your mouth feed on sugar and excrete lactic acid. It's part of their metabolism. Wikipedia has more details about dietary sugars and acidity in mouth. It's not clear from the chart what part of the body it refers to, or what it claims the acidity to cause. But it does sound ...

9

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

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On the point of ‘makes your body acidic’ you already have an answer to which I have nothing to add. However, you also claim that sugar be completely neutral—at which point I must intervene. A lot more compounds can act as acids and bases than the shortlist of common acids you probably had in chemistry class. Most things with a lone pair can be a base and ...

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

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 ...

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 ...

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

Octane is a specific molecule with 8 carbons normally found among the many different molecules in gasoline. Pure iso-octane (2,2,4-trimethyl pentane) was chosen as the reference fuel standard for resistance to preignition for gasoline fuels. So the octane number of a fuel is a rating of the preignition potential of that fuel compared to a fuel containing 100 ...

5

Water freezing into ice EXPANDS. ($\ce{H2O}$ is most dense at $\pu{4^\circ C = 39^\circ F}$) - https://sciencestruck.com/density-of-water. In other words, water expands BOTH as it cools below $\pu{4^\circ C}$, AND as it warms above $\pu{4^\circ C}$. When ice comes out of the freezer, it is typically well below $\pu{0^\circ C}$. It may be at $\pu{-10^\circ C}... 5 As mentioned in the comments, this topic can become exceedingly complex if all the aspects of current-gen photochromic lenses are brought to the table (and I'm sure a lot of it is locked away in trade secrets). My goal here is to provide some insight into the chemical/physical mechanisms at work. Photochromic sunglasses are a smart new application of very ... 5 You don't have to reinvent the wheel. Food industry already uses quite simple oxygen scavengers for decades, and one of the most affordable formulations include iron powder mixed with sodium chloride. Typically, an oxygen scavenger is packaged in small packets (sometimes labeled as "oxygen absorber" or "antioxidant") that are added with the product inside ... 4 I'm quite surprised no one stated the obvious: formation of F-centers in the crystal lattice of$\ce{NaCl}$. Despite the fact that in nature blue rock salt is rare, it's quite easy to synthesize some in the lab by heating metallic sodium and sodium chloride in an enclosed vessel.$\ce{Na}$vapor is capable of dissolving in the crystal lattice formed by$\ce{...

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 ...

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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

Octanes are components of fuel. There is also such concept as "octane number", used to determine quality of gasoline. Higher octane number = higher activation energies, and higher $E_a$ = lower chance of uncontrolled ignition = higher cost per liter. "Gas station numbers" for fuels are octane numbers. You can see (I think) numbers from 87 to 97 (depends on ...

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{...

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