# Tag Info

12

I'm studying chemical engineering for more than two years and what I can tell you is that is not really a lot of "good" books you may read as an introduction. You have to understand that Chemical Engineering contains both "Chemical" and "Engineering". The first one refers to chemistry whereas the second refers to the way to make something. I mean a ...

8

It's hard to maintain homogeneity for the mix of powders. The bigger the batch, the less homogeneous it's going to be. Ideally you want to disperse solid ingredients; there are several techniques to do that. Two of the most popular ones are: dissolving all the components in a non-reactive solvent and they dry out or precipitate the powder; using a ball mill....

6

I'll answer the question in general of how Hydrogen and Oxygen can coexist in metastable mixtures at higher temperatures, though without hazarding a guess for your specific case. Like you and others, I'd be very surprised if your bulk gas is actually well mixed at $\pu{900 ^{\circ}C}$ without exploding! It's far enough beyond the autoignition temperature, ...

6

There is a book The Design of Controlled-atmosphere Chambers for the Study of Oxygen Toxicity, so I suggest "contolled-atmosphere chamber".

5

I can speak based on my experience studying chemical engineering as an undergraduate at an ABET accredited university in the United States and working in industry. A typical curriculum would include a focus on fundamentals which can then be applied in specific industries or in different cases rather than an in depth study of specific manufacturing processes ...

4

First of all, cracking is not an equilibrium process, therefore La Chatelier-Brown principle doesn't apply! (irrelevant) Also, the mechanism is much more complicated than this: In gas phase, radical reactions generally have extremely complex reaction networks. E.g. burning of methane with oxygen contains thousands if not more elementary reactions. I am ...

3

Thermodynamic properties are functions of composition, which can be represented as $(\chi _1,...,\chi _N)$ where $\chi _i$ is the mole fraction of component $i$ present in the system. Now imagine a change in the composition such that the amount of component $i$ is increased by a very small quantity $dn _i$ (alternately, imagine the system to be infinitely ...

3

Phenols react with aromatic acid chloride in the presence of a base such as $\ce{NaOH}$ at room temperature. Such reactions are called Schotten-Baumann type reactions (Ref.1&2; both are in German). The Schotten-Baumann reaction is an organic reaction used to convert an acyl halide or anhydride to an amide, if reacted with an amine and base, or an ...

3

Just three points why omitting a solvent might not be a good idea without experimental evidence that support the contrary: There is a reason many organic syntheses are run with reagents in a concentration in range of 0.1 to 1 mol/L; to moderate both rate (kinetics) and heat (thermodynamics) of a reaction. The omission of a solvent for an already exothermic ...

3

According to this source: The popular EoSs such as Soave-Redlich-Kwong (SRK) [1] and Peng-Robinson (PR) [2] predict liquid density with an average absolute error of about 8%, much higher than several good density correlations. This large magnitude of error is not acceptable by industry; therefore, they are not used for this purpose. Which is what I ...

3

You could theoretically boil at the higher temperature but why would that be a requirement? Why would you require reflux specifically if you can actually heat the formic acid to higher temperatures under pressure? Heating should work on its own and degassing to drive the equilibrium should work with a back pressure regulator. However, most lab glassware ...

3

With 6 components and 4 reactions, you must have two conservation rules (that is, if the reactions are independent, which they are). Mathematically, we find ourselves in a 6D space (as there are 6 components), we move in a 4D subspace defined by the 4 reactions, and we need a basis for the 2D subspace normal to it, which is precisely where we can't go. The ...

3

The relevant property is the temperature of the burnt fuel when it leaves the rocket engine nozzle, i.e. when it stops exchanging impulse with the engine. That temperature you can convert into a velocity distribution of the gas particles, multiply with their molar mass, and that's it. (somewhat less than that of course, because no all gas particles are ...

3

What you do is write $[D]=[C]K_{CD}$, $[C]=[B]K_{BC}$, and $[B]=[A]K_{AB}$. So, $$[C]=K_{BC}K_{AB}[A]$$ and $$[D]=K_{CD}K_{BC}K_{AB}[A]$$So, $$[A]+[B]+[C]+[D]=(1+K_{AB}+K_{BC}K_{AB}+K_{CD}K_{BC}K_{AB})[A]=10$$

3

Lacking additional information, answers likely will be speculation-based only. To mention a few factors to consider: Stating GC-MS analysis only states, that there is technique to separate compounds by different rate of retention over a stationary phase (gas chromatography, GC) combined (a.k.a. hyphenated) with an other technique to analyze fractions ...

2

UNIFAC is not a procedure, unless by chance in a similar field two things got the same name, which is unlikely. UNIFAC is used by activity coefficient models for predicting liquid properties. It is often coupled with a vapor phase equation of state, and quite often simply the ideal gas law... A flash point calculation is a procedure, and must be done in ...

2

This is the heat equation analogue to Ohm's law, in which resistances are additive (in series), and hence the inverse conductances are additive. The way to reason is that the full equation (1) for the heat conductivity (1) contains three terms: one for the interior of the tube, one for the tube wall, and a third for the exterior. When you look at the ...

2

If the LiH needs to be exposed to ambient conditions, it should be enclosed is a moisture-impermeable container, e.g., a glass ampoule which is closed off. Glass can be blown quite thin - but then you need to be quite careful. As DrMoishe suggested, PE or PP would be good, but I'm thinking of it as a closed tube, not as a binder.

2

You calculated 83.3 moles of air reacting with the ethanol. Since air is 21% oxygen, this means that 83.3 x 0.21 = 17.5 moles of oxygen react with the ethanol. Since each mole of ethanol reacts with 3 moles of oxygen, the number of moles of ethanol that react is 17.5/3=5.833 moles ethanol. Since the fuel mixture is 90% ethanol, there are 10 moles of fuel ...

2

I think you overcomplicate the problem. There are many variables you don't need and many components that are duds (nitrogen, water, pressure). What important is that we burn ethanol: $$\ce{C2H5OH + 3 O2 -> 2 CO2 + 3 H2O}$$ so that the ratio between ethanol and oxygen is $1:3$. I have taken chemistry engineering classes long time ago and I don't remember ...

2

You're confusing different enthalpies (don't worry, it seems to be rather common). Let's stick with NO as an example. The standard enthalpy of formation, $\Delta_fH^\circ$, is defined as the enthalpy of the reaction $\ce{0.5N2 + 0.5O2 = NO}$ at any given temperature. That is, if you need $\Delta_fH^\circ(298\textrm{ K})$, or $\Delta H^\circ_1$, your reaction ...

2

Automatic pH control is not that easy as is shown by the fact that automatic titrators, the equipment that you want to build, are relatively expensive. Besides titration, automatic titrators usually have also a pH stat function, which is for maintaining a certain fixed pH. In first place, note that to have a good control, typically you must know which ...

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The liquid phase is above the surface. The vapor phase is below the surface. The planar cut at a constant temperature is easiest to understand. The bottom curve will show the composition of the liquid phase as a function of molar fraction, and the upper curve will show the composition of the vapor phase. Likewise for the curves of molar fraction versus ...

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No. In all but highly exotic situations, diffusive and convective fluxes of solutes are linear in the solution-phase concentration of the species: \begin{align} J &= -D {\mathrm dC\over \mathrm dx} & \mathrm{(diffusion)} \\ N_c &= k_c\left(C_\infty - C_\mathrm{surface} \right) \quad & \mathrm{(convection)} \end{align} Whatever the ...

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No expert here, but cullet would react faster than sand with the alkali, developing into a more uniform fluid that can be mixed at a (slightly) lower temperature so as to eventually dissolve the sand. It is like beginning the reaction to produce glass at 25% (or however much cullet is used), rather than 0%, so that raising the temperature is not needed to ...

2

You can certainly turn electromagnetic energy into chemical energy, but the key is 'efficiently.' A photo-voltaic cell can be used to split water into Hydrogen and Oxygen. The Hydrogen can be burned or used in a fuel cell. But the key is how efficient is 'efficient.' Each step will lose energy, but if solar is the input, there is a huge supply. If a solar ...

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Zinc is used in some silver alloys; Zn would be easy to lose into dross or vaporization.

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The only three terms that need to be taken into account are $\dot{W}$, $\Delta \dot{E_p}$ and $\Delta \dot{E_k}$, as there's no heat involved. I use the 'dot' notation to indicate these are energies per unit of time (powers). For potential energy power we have: $$\Delta \dot{E_p}=-\dot{m}gH$$ Here $\dot{m}$ is the mass flow ($275\ \mathrm{kg/s}$). For ...

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In Fabrication of Microstructures by Wet Etching of Anodic Aluminum Oxide Substrates Chem. Mater. 2005, 17, 4049-4052, 5% phosphoric acid is used and is selective relative to aluminum, but you need to check how it would do with respect to the other metals you mention Finally, the AAO substrate was wet-etched in a 5 wt % H3PO4 solution at 20 °C for 8 h

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When a reaction is at equilibrium, there will be stochastic fluctuations. These are usually not measurable (for example, if we have more than a mole of products and reactants in our reaction mixtures). In this specific case, the fluctuations are easy to measure because the total number of antigen molecules per cell is countable, and you are separating cells ...

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