# Search results

1. ### Submarine Modeling

it would be very cool if you solve that with integrals, but its a lot more than you need, really
2. ### Thermodynamics Help

I used that book for thermo 2, and I hated it. Try using Wark's or Cengel's. If you want a more theoretical approach, you can go for Callen's "Thermodynamics and an introduction to thermostatistics"
3. ### Can anyone check this identity please?

yes, actually, I was trying to take the curl of the Navier-Stokes equation, to get the vorticity equation, a problem in Bird's transport phenomena, the book asks you to deduce it in two forms, the first one is the one I have already, the second one involves the Levi-Civita symbol and I'm...
4. ### Can anyone check this identity please?

I know now, thank you. Actually that "identity" es not true unless Div(v)=0, because another term is missing. However that fits perfectly since I am working with fluid mechanics. Thanks again!
5. ### Can anyone check this identity please?

I finally found it, looks like I was missing another term in the right side v(Div(v)), altough this is 0 in my case because I am working with fluid dynamics. Now everything makes perfect sense, thanks anyway
6. ### Can anyone check this identity please?

is this identity true? V is a vector, so VV is a second order tensor I have tried to prove this but the components of the tensor appear always as operands of the nabla. Thanks! Div(VV)=v.(Grad(V))
7. ### Can anyone check this identity please?

Homework Statement I just want to check if this identity is true, since I have not found it anywhere, can anyone help me? v is a vector (and that nu is supposed to be a v too)
8. ### Nucleophilicity of an aldehyde

Yes, actually I want to do the molecule attached, as you can see, it is not an activated system, that's why I thought I could use aromatic nucleophilic substitution
9. ### Fluid mechanics book for ChemE

Hi! Im a student in chemical engineering and I would like some recommendation for a fluid mechanics book, I've been using Bird's Transport Phenomena but it seems to be a bit difficult to follow it, as it skips a lot of steps.
10. ### Nucleophilicity of an aldehyde

Does anyone know if an aldehyde, specifically, acetaldehyde behaves as a good nucleophile? I'm trying to insert an aldehyde in an aromatic compound through an aromatic nucleophilic substitution, any information or source to pKa data would also be appreciated, thanks!
11. ### Synthesis of an organic compound

Homework Statement I've been asked to explain how would I synthesize an organic compound, its structure is attached as an image (first attachment) , could you help me figure it out? I'm supposed to start from benzene The Attempt at a Solution So far, I've got a big part of the...
12. ### MATLAB: expressing a double index equation as a matrix

oh thanks a lot Grep, that REALLY helped me, now I've finished :)
13. ### MATLAB: expressing a double index equation as a matrix

well, the problem is that my equation is not so simple, it is actually a pretty big fluid dynamics model for calculating the viscosity of a mixture of 10 gases, so I have an equation, lots of constant properties, and I am trying to get a 10x10 matrix :S
14. ### MATLAB: expressing a double index equation as a matrix

like for example, if I have Iij=vi/vj considering that I know v for every i or j
15. ### MATLAB: expressing a double index equation as a matrix

Just an urgent doubt, I am new to matlab. So imagine an equation that has two indexes, and that can be expressed as a matrix, how can I do something like this in Matlab? using a for cycle?
16. ### ( ) Power series solution for ODE

(URGENT) Power series solution for ODE Homework Statement Supose there is an infinite series solution\sum b_{n}x^{n} for u''+4(x-(1/4))^2*u+C(x) = 0 where C(x) is a function (I get it in another problem, I'll put it in the relevant equations area), determinate the coefitients b_{0} b_{1}...
17. ### Thermodynamics problem help

No, I am actually trying to find the intermediate pressure for a 2 step compression so that the work needed is minimum
18. ### Thermodynamics problem help

thanks a lot both of you, now, just another doubt, is H=C_P\Delta T+H_0 valid only for ideal gases? because I am working out another problem now, and I was planning to use the equation I got in this problem, but now it is not an ideal gas, it is air at about 25atm, is the equation valid?
19. ### Thermodynamics problem help

Homework Statement A unit mass of an ideal gas at temperature T undergoes a reversible isothermal process from pressure P 1 to pressure P 2 while loosing heat to the surroundings at temperature T in the amount of q. If the gas constant of the gas is R, the entropy change of the gas ∆s...
20. ### How to not mistakes with long calculations

LOL I know, but I will make an effort not to forget my math, I love math too much to just forget everything

22. ### Help with thermodynamics problem

yeah, well, what i am interested in , is in finding how can I get that equation listed above, I had thought in deriving the equation for the sum of work in each phase, and finding the minimum value, however i can't set the whole thing to get that equation. Can I consider the air as an ideal gas...
23. ### Help with thermodynamics problem

cmon, help me, please, how do you obtain that equation?
24. ### Help with thermodynamics problem

Homework Statement Hi I would like you guys to help me with this problem Air is to be compressed steadily and isentropically from 1 atm to 25 atm by a two-stage compressor. To minimize the total compression work, the intermediate pressure between the two stages must be (a) 3 atm (b) 5 atm (c)...
25. ### I with implicit derivatives

why don't you just check another book?
26. ### Math Should I switch to Mathematics?

I know it is useful for me, at some level, but since I share the class with pure chemistry and biology students, there are many things on the program that are not very useful for a chemical engineer, reactions that are only useful in the lab, for example there are lots of methods for producing...
27. ### Math Should I switch to Mathematics?

I'm studying the second year of a chemical engineering degree. I have always loved mathematics, and I am pretty good at them, and since the beginning I am not satisfied with the engineering approach to mathematics, I would like to learn some more complicated math, but I'm not quite sure if I...
28. ### How to not mistakes with long calculations

when its too long, it's okay to use a computer, however, don't become lazy, because probably you will need to know how to do it without a computer, for example, I've got a friend that is studying physics, and I am studying engineering, he would often talk about how great his math classes are...
29. ### Can Hydrogen be made from air and water?

well, I already got a warning for answering just like that, so why don't you calculate it yourself? just look for an enthalpy table and use Hess's Law, draw some lewis's structures to know which bonds are broken and which are formed
30. ### Can Hydrogen be made from air and water?

also water is very stable because of hydrogen bonds , if you want to produce Hydrogen gas just add an inorganic acid to some metal, like HCl and Al for instance, there are many other ways, like electrolysis on water
31. ### Engineering Moving from Chemistry into Chemical Engineering

it's just personal choice I guess, I'm studying chemical engineering already
32. ### Engineering Moving from Chemistry into Chemical Engineering

I would go for the PhD.
33. ### What happens when an acid or base reacts with a metal, for example, Mg.

2HCl+Mg-->MgCl2+H2
34. ### Can Hydrogen be made from air and water?

no, it is not possible, ammonium nitrate is ussually produced mixing nitric acid and ammonium hidroxide, HNO3+NH4OH--->NH4NO3+H2O you want to blow something up huh?
35. ### Spivak calculus on manifolds

well, I paid for both of his calculus books, how could I not? they are simply great, but anyway books in Mexico are a LOT cheaper than in the US, I don't really know why :S.
36. ### Spivak calculus on manifolds

well I do have the material book, and a PDF, but it is in spanish, I don't remember where I found it
37. ### Studying Good chemistry books/videos/tutorials?

Check out the MIT opencourseware, they usually have good videos, as for good books, it depends on the topic you want to study, a good all-round book is Petrucci's Chemistry. For organic chemistry I would recommend Wade, or Voldhart (I hate Carey and McMurry) for inorganic chemistry it really...
38. ### Best Chemistry Book?

Hi, well I'm in chemical engineering, and I own Petrucci and Whitten-Davis, those are pretty good, Whitten's book has very nice graphics and both have a wide variety of problems, I've heard good things about Brown's Chemistry: central science too, Kotz is also a very nice one, and Chang's...
39. ### Help with Euler's Method in Matlab

It worked!, thanks a lot
40. ### Help with Euler's Method in Matlab

Homework Statement Well, I'm having problems with this script, I'm taking my first course on differential equations, and I am trying to write a script that approximates the values of the solution of a differential equation, and compares them to the exact solution using a table of values, it...