A.K.
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Why isn't 'chemically-strengthened glass' made with potassium carbonate to begin with?
45 votes

The potassium is not added first because the potassium does not intrinsically make stronger glass, it is the substitution of a larger ion for a smaller one at the surface that does. To understand why ...

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Is an isobar the same as an isotope?
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33 votes

Not quite, an isotope has same number of protons ($ A- N = Z = \mathrm{constant}$), but a different number of neutrons ($\mathrm N$ varies; e.g. $\ce{^3_\color{red}{1}H}$ and $\ce{^2_\color{red}{1}H}$,...

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When a candle burns, why does the top of wick glow if bottom of flame is hottest?
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32 votes

The wick temperature does not have to be the same as the flame temperature.The flame is hottest at the bottom, but the wick is hottest at the top. For a candle, the wick burning isn't the intended ...

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What's this glassware?
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26 votes

The glassware shown is a drying tube. The bulb holds cotton or glass/quartz wool while the tube part holds a drying media such as anhydrous calcium sulfate to keep moisture out of the vessel during ...

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What makes Gorilla Glass more durable with each generation?
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20 votes

Are there other ways of "chemical strengthening" besides cationic exchange that can be utilized to strengthen the glass, keeping it flexible and less fragile at the same time? In a word: No. To ...

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Why do the physical properties of an egg shell change when the egg shell is exposed to vinegar for a week?
19 votes

It doesn't make calcium carbonate rubbery, it removes the calcium carbonate. Egg shells are not purely calcium carbonate they are more like a composite with a continuous matrix of calcium carbonate ...

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What is the pH of ice?
16 votes

$\mathrm{pH}$ is the aqueous concentration of $\ce{H3O+}$ or $\ce{H+}$ ions in soution. I would not say that ice lacks $\ce{H3O+}$ and $\ce{OH-}$ ions as ice's structure would allow for such, however, ...

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Why does ice crack when a drink is poured on it?
15 votes

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 ...

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Why does lavender oil dissolve plastic?
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15 votes

Based on appearance and extent of deformation, your bottle is likely made of PVC plastic which is not compatible with oils. Plastic bottles are made from blow molding. This process leaves residual ...

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Why do atoms need 8 electrons to stabilize?
14 votes

The valence orbitals of atoms are composed of suborbitals (s and p) there is 1 s suborbital which is spherical and can hold 2 electrons (one with up spin and one with down spin). There are 3 p ...

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Why is Borax used as a primary standard?
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12 votes

Yes borax is a hydrate, but the reason it is favored for titration is that it gives consistent results, which to most scientists, is far more important than accuracy. The $\ce{ .\!10H2O}$ hydration ...

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Can gases be "immiscible"?
12 votes

Good question but there is no such thing as immiscible gases. Immiscibility is caused by surface energy/tension. Gases do not have surfaces and therefore lack surface tension.

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What temperature is required to burn pencil lead graphite?
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11 votes

You have two problems. 1.) pencil lead graphite is actually a graphite-clay composite. 2.) carbon does not sustain burning easily unless it is held at very high temperatures. Pencil lead will not ...

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If graphite's just a huge polymer of benzene why isn't it an aromatic compound (polymer?)
10 votes

Graphite/graphene is aromatic. The first image below is a common crystallographic representation of graphite and does not account for covalent bonding. The second one shows the molecular structure of ...

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Why a low conductance ion such as lithium is used in batteries?
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9 votes

The conductivity values you cite are for ions in water. there is no water in a lithium battery otherwise, it would explode and burn before leaving the factory. Beside low conductivity can be ...

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What happens to the bleach after mopping?
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9 votes

What happens to the acid in the bleach? First of all there is no acid in bleach. In fact bleach uses base, the antithesis of acid. and is essentially chlorine dissolved in a solution of sodium ...

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How is silver chloride more soluble in brine than water?
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8 votes

I mean won't the common ion effect operate? The common ion effect always applies for pure substances. With the added sodium chloride, you have changed the effective solvent and changed the ions. Or ...

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Why does Coca-Cola Zero Sugar Contain Sodium Despite no Sodium Ingredients?
8 votes

Two sources: water and natural flavors According to the Wisconsin department of healt natural sodium levels in water is $\pu{40-60 mg/L}$ meaning a $\pu{20 fl oz (\! 591 mL)}$ Coke has about $\pu{25 ...

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Does mercury amalgamate with Brass or Steel?
8 votes

Brass contains zinc and copper. Both of those materials will readily amalgamate with mercury and thus it is not recommended to allow brass to contact mercury. Steel will not form an amalgam and is ...

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Do light and heavy water form an azeotrope?
8 votes

This is a good question, but no, there is no azeotrope in any isotopic mixture, as an azeotrope requires non-ideal mixing of two components to form a minimum or maximum critical point on the plot of ...

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Is there a way to "electroplate" wood with copper?
8 votes

Dip the wood in a solution of ascorbic acid (Vitamin C; orange juice will do) and soap and allow it to soak. Soaking time will vary by wood variant. then dip the wood in a solution of copper sulfate ...

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Why is fullerene 60 an insulator while graphite is a conductor?
8 votes

To reiterate Ivan's comment fullerene is a bad conductor because that's what the measured properties produce as a result. The mechanism that makes it a bad conductor is that it has shorter range ...

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Is it possible to boil a liquid by just mixing many immiscible liquids together?
7 votes

Is it possible to boil a liquid by just mixing many immiscible liquids together? No*, boiling is when the vapor pressure of a phase is greater than the ambient pressure. You might create a total ...

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Is there such a thing as a "minimal soap" molecule?
7 votes

While I agree that the definition matters I disagree with the definition of soap as "as the salt of a fatty acid". For one SDBS, AOT, SDS, Cocamide DEA (not even a salt) and CTAB are all popular soaps ...

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pH of solution after adding SiCl4
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7 votes

Silicon is very oxophilic and $\ce{SiCl4}$ irreversibly hydrolyzes in water as follows: $$\ce{SiCl4_{(l)} + 4 H2O_{(l)} -> 4 HCl_{(aq)} + Si(OH)4_{(s)}} $$ The release of $\ce{HCl}$ creates ...

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Why is barium used instead of bismuth as a contrast in gastrointestinal xrays?
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6 votes

Is it less expensive? Yes, but not so much that it would be favored, i.e. you don't worry about saving \$5 when your doing a \$5000 procedure. Is there a particular property of barium that makes ...

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How does the room gets heated by leaving a fridge open?
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6 votes

Also the radiator emits out the heat in the surrounding. Thus the heat absorbed from the room is released in it and the must neither get cooled nor heated. You have forgotten a few parts to your ...

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Do all flames require the same minimum concentration of oxygen to sustain themsleves?
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6 votes

No, different substances will cease combustion at different concentrations of oxygen. The concentration needed can be described by the limiting oxygen index. This is the reason that the use of pure ...

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Bond lengths in naphthalene
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6 votes

You are assuming that all resonance structures contribute equally. The resonance structures on the right and left are equivalent but have one aromatic ring and one non-aromatic ring. This is in ...

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Why is benzoic acid a stronger acid than acetic acid?
6 votes

It is all about the electron withdrawing/ donating nature of the acid's functional groups. The more electron withdrawing the group, the stronger the acid will be. The more electron donating the ...

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