# Tag Info

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Let's divide the steel world into two classes: 1) rusting steel and 2) stainless steel. Rusting steel, in the presence of oxygen and moisture, will oxidize, forming hydrated iron oxides/hydroxides which have a greater volume than the original iron, and which have relatively little adhesion to the metal. They curl up and continue to expose bare metal, and so ...

19

It is usually a bulk property though you would need to know exact regulations for your country to be certain. Stainless steel is steel (i.e. iron + a little bit of carbon) alloyed with another metal which makes it resistant to oxidation by atmospheric oxygen (usually chromium). It does not mean though that it would resist to strong acids (e.g. concentrated ...

10

"Stainless" is not a specific definition. The stainless steel with the least alloy is $5\% \; \ce{Cr}$ ( grade 501) according to AISI (It can't be cut with an oxygen/acetylene torch-like regular steel). API considers $\ce{Cr :Mo}$ (9:1) as stainless for oil well tubulars. SAE consider $12\% \; \ce{Cr}$ as stainless (most modern auto exhaust pipe). Stainless ...

9

You did the right thing by neutralizing with a base. The best solution is to let time heal the stain. The surface is obviously damaged, but there is no way to reverse that damage. The stain will only go away if someone keeps on scrubbing the area until a new surface is exposed. The good news is that dirt, soil, and water will slowly remove and even scrub ...

7

Quick and simple: Steel = iron + carbon (less than 2%; also called "forgeable iron") Adding chromium (min. 12 %) makes it stainless. These chromium atoms are spread over the full volume of your block, also on the surface of it. There they create a thin layer of oxygen atoms. This layer makes the steel stainless. So when you cut your block in half, a new ...

5

The ratio $$\frac{x}{m}= k P ^{1/n}$$ can be re-expressed in terms of the area $A$, surface-to-volume ratio $\lambda$, and density $\rho$ (note that $m=A\rho/\lambda)$: $$\frac{x}{A}= k' P ^{1/n}$$ where $$k'=k\rho/\lambda$$ The advantage of using $k$ as opposed to $k'$ is that you don't need to determine $\lambda$ to know how much (as in, what mass) ...

4

While I can't find specific justification for the surface, the first competition involved both gold and silver "racetracks." Drivers gear up for world’s first nanocar race How to build and race a fast nanocar The competition involves propulsion and imaging using STM so the substrate must be conductive. Gold (and silver to a lesser degree) is particularly ...

4

Rather $$\ce{2 NaOH(aq) + CO2(g) -> Na2CO3 (aq) + H2O}$$ and analogically on the solid $\ce{NaOH}$. Bicarbonate in aqueous solutions cannot survive the excess of hydroxide, forming carbonate. $$\ce{HCO3^{-}\ (aq) + OH- (aq)<=>> CO3^{2-}(aq) + H2O}$$ The same is further enforced by dehydration effect of solid hydroxide. \ce{NaHCO3(s) + ...

2

The paper of interest is C.M. Wolfe et al., "Growth and Dislocation Structure of Single-Crystal Ga(As$_{1-x}$P$_{x}$)", Journal of Applied Physics 36(12) 3790 (1965). The key paragraph is: The GaAsP of this investigation has been prepared by a closed-tube method utilizing a quartz ampoule which is cleaned and baked-out under vacuum near the ...

2

If you are confused about the electrical double layer, it is completely fine because electrochemists spent several decades to understand it and yet the concept remains "grey" in the minds of most electrochemists. You will find different stories and versions on the web and of course different terminologies. Your understanding is correct but I will call the ...

2

The Joint Entrance Examination board should update their outdated set of questions relying on rote memorization. Why do they assume the student has to memorize the charge of the ferric hydroxide particles and in what medium? Charge on the colloids is dependent on the medium and pH! They should also mention that the molar concentration of the anions is the ...

1

You can think about this problem from the definitions of surface energy. The surface energy quantifies the disruption of inter-molecular bonds that occurs when a surface is created The composition or structure of a surface depends on how the bulk crystal has been cut. The electronic structure (or number of dangling bonds) depends on surface composition ...

1

Agreed: unless air is pushed through the activated charcoal bed, few impurities would be adsorbed. It would depend on how tightly the substance clings to the carbon, i.e. it would vary with impurity, but Trox Technik KS Filters recommends, "saturated activated carbon is reprocessed... with a gradual increase of temperature from 20 to 830 °C and a delay ...

1

You can argue that the effect of the solid is to "seed" formation of the condensed phase, as a set of interactions that lower the chemical potential below that of the gas, leading to "condensation" (well, adsorption). This is all very approximate as the details matter of how (as in, through what interactions) the adsorbent interacts with the gas molecule. ...

1

2 mm drops of any liquid in any other liquid will be very unstable, and will grow to be an entire layer. Perhaps you could buy some plastic spheres of the size you desire, made from plastic slightly heavier than water. Then you can adjust the rate of fall by thickening the water. If you use an organic thickener, like xanthan gum, you should probably add a ...

1

You may ease the droplets of water to "fall further down" across the oil by adding some of dishwasher into the water. As just tested with a glass filled with some of sunflower oil, the water-dishwater droplets reaching the surface air./.oil will deform and flatten when they fall from about 30 cm above on said surface. Eventually however, cohesion and ...

1

As correctly identified, the Langmuir model assumes a monolayer of adsorbed molecules. The adsorption cross section of an adsorbate depends on numerous factors, not just the molecular size. Furthermore, the observed specific surface area is scale variant, similar to the length of a coastline. A phenomenon known as fractality. That mean that the measured ...

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