Chemical Definition and 1000 Threads

Homework Statement In chemical reactions, when energy is released, mass is lost according to Einstein’s formula just as it is for nuclear energy (though the amounts lost are so small that for centuries scientists thought that mass was conserved). When a kilogram of coal is burned, it...

Homework Statement 5. [1pt] For each of the following, indicate whether the statement describes a physical (P) or a chemical (C) change. Answer, in order, with a single string, e.g. CPCPC -- NO SPACES, NO PUNCTUATION. a) A grease spot is removed with cleaning fluid. b) Sodium...

I am in a dilemma. Next fall I will be attending a university (as a freshman), and will be majoring in chemical engineering. Now my question is, I really LOVE physics, and how it relates to the real world. Is there anyway that I can pursue physics later in my career after I received a...

I was wondering what (I) means when it is written after a chemical compound, for example, H2SO4 (I). Thanks!

Hi, Homework Statement Consider a mixture of different gases with N_i molecules each (i=1...k denotes the species). For ideal gases the following relation yields: S(T,V,N_1,...N_k)=\sum_{i=1}^k S_i(T,V,N_i) a)Give explicit expressions for the entropy, the internal energy, Helmholtz free...

Chemical engineering not as popular as other 3 "big" engineering branches? It seems to me chemical engineering is not as popular as the other 3 "big" engineering branches (civil, mechanical, electrical). If true, what's the reason for this? Lower demand? More challenging? Less glamorous?

What determines an atom's chemical fingerprint (banding pattern)?

[b]1. okay so the equation is: 3A+2B---->C+D K=1.00x10(to the negative third power) A=9.5-M C=0.0200-M D=0.0200 what is B ? [b]3. the answer is either 1.24: 0.0216: : 0.00180 : or 0.110 (i don't remember) so what i don't get is HOW DO I SET UP THE PROBLEM? :confused: go step...

Can anyone please explain to me what is reaction mechanisms and intermediate? I have read my book many times, but I don't get it. Also, it would be great if you can me some examples about them. Thank you for your help!

Homework Statement Give the formula to show the reactants and products for the following chemical reaction. The reaction occurs in aqueous solution unless otherwise indicated. Represent substances in solution as ions if the substance is extensively ionized. Omit formulas for any ions or...

Hi all i wan check my answer Blance the chemical by algebric method ?

Can a catalyzer in a reaction be an intermediary as well? Im not sure, i don't think because it would have to consume it self...

Two chemicals, A and B, are combined, forming chemical C. The rate of the reaction is jointly proportional to the amounts of A and B not yet converted to C. Initially, there are 50 grams of A and 80 grams of B, and, during the reaction, for each two grams of A used up in the conversion, there...

Homework Statement In the reaction between H2O2 and I-, 15 mL of 0.30M KI, 75. mL of 0.10M H2O2 and 21 mL of 0.020M Na2S2O3 were mixed in a flask containing starch and buffer and the total volume was made up to 500mL with distilled water. The solution turned blue (indicating the presence of...

So I'm taking chemistry again after a five hear hiatus from the topic and I would really appreciate an explanation on a certain formula. magnesium +oxygen forms magnesium oxide Mg+O2=MgO My question is, what happened to the 1 of the oxygen atoms? Shouldn't it be MgO2?

Homework Statement 1. According to the mechanism below, what is the correct expression for the rate of consumption of A? In the mechanism, M is a molecule that collides with A and A* is a highly-energized form of A. Step 1 (reversible): A + M <---> A* + M rate constants k1 and k-1 Step...

Homework Statement 35.0mg of C-H-N (the unknown is the empirical formula) combusts to produce 33.5mg CO2 + 41.4mg H2O Homework Equations I'm confused by the fact the product does not include N so I'm unsure how to figure for it. The Attempt at a Solution Using all the information...

Hello, right now, I am learning thermodynamics with Reichl: "A modern Course in Statistical Physics" In chapter 3.C page 100 "classification of phase transitions", the text says: "As we change the independent intensive variables (p, T, x_1,... ,x_l) of a system, we reach values of the...

Hi. This is to all the practicing EEs out there. What are some of the challenges of electrical engineering work? Is it varied? What is your role (esp. wrt to EE technologists/technicians)? Preferably, answers will come from various specialties and roles (please state them). For example...

Hello, I am very new to the forums, and I ran across another form discussing these two topics; however the previous thread was mainly discussing nanotechnology. I am interested to find out which carrier I should pursue: chemical eng. or Elec. Eng.? I am extremely interested in both...

Hello! Does anyone have a free ebook of Chemical Thermodynamic by Peter Rock A.?

Homework Statement Balance the following Chemical Equation (x1)KMnO4+(x2)MnSO4+(x3)H2O->(x4)MnO2+(x5)K2SO4+(x6)H2SO4 Homework Equations Here is the matrix I came up with but it seems to be flawed but I am unable to see what i am doing wrong 1 0 0 0 -2 0 (K) 0 1 0 -1 0 0 (Mn) 4 4 1...

Are there any good websites to learn chemical names? I can only find ones that teach a few things, but not everything. I need to be able to know the chemical name just by looking at the formula and vice versa.

Can anyone help me. I am very confused about the chemical potential. In the following equation dU = TdS - pdV + u dN, where u is the chemical potential it seems to me that if you add particles to a system you are increasing the energy of that system, i.e. the chemical potential is...

Homework Statement The chemical potential energy in a certain amount of gasoline is converted to kinetic energy in a car that increased its speed from 0 mph to 32 mph. The car accelerated to 64 mph. Compared to the energy required to go from 0 to 32 mph, the energy required to go from 32 mph...

i'm not exactly sure what i want my future career to be (my interests keep changing) but right now I'm set on engineering. i did a little research and I've narrowed it down to either chemical or systems design engineering. if there are any chemical engineers out there, why did u choose this...

I've been independantly studying chemical kinetics from a standard freshman year chemistry textbook, and I enjoy the subject, could anyone suggest any further reading or sources? Specifically I'd like to try and find a calculus based text, as the one I have specifically avoids using any...

I'm assuming the standard reductionist viewpoint: that chemistry is simplified quantum physics. Of the four fundamental forces in modern physics, what forces play a role in chemical reactions? Is it safe to assume it's solely electromagnetics?

Hey guys, I'm currently a sophomore chemical engineering major and I'm looking to do an REU related to physical or organic chemistry, or chemical engineering applications. I know most people here would be math or physics or other engineering majors, but I'm just wondering if anyone who had a...

Homework Statement http://carlodm.com/pictures/problem.png The Attempt at a Solution I'm stuck. Usually I balance the equation by multiplying the Fe(OH)2 and Fe2O3 by 3. However, I can no longer do this because Fe2O3 has two iron's per one molecule. Do I multiply one by 6 and...

Homework Statement What is the chemical potential, \mu (in units of \hbar\omega) at T = 0 K of 44 ^{6}Li atoms with spin 1/2 contained in a 3D harmonic potential well (energy levels, \epsilon_{i}=(i+3/2)\hbar\omega with degeneracies g_{i}= 1/2(i+1)(i+2) )? Homework Equations The...

Homework Statement Derive the following: \mu_i=T\left( \frac{\partial S}{\partial n_i}\right)_{U,V,n_j\not=i} \mu_i is the chemical potential of the ith component G is the Gibbs free energy Homework Equations dU = TdS - PdV + \sum_i \mu_i dn_i \mu_i =...

If our solar system originated from the same dust / gas cloud, why do we see such differences in abundance of elements from one body to another. I can come up with two possible answers: 1. Rotation of cloud centrifuged heavier elements towards edge (Almost certainly not true, because it would...

Homework Statement Calculate the change of chemical potential of CH4 in a transformation from the initial state using the ideal gas law. σi={pi=1atm, Ti=298.15K} to the final state σf={pf=100atm, Tf=400K}. any ideas?

Just out of curiosity, has anyone ever heard of using sodium thiosulfate pentahydrate (liquid crystals) as a viable method of heating a house? I'm doing a project on this now and it seems hugely inefficient due to the massive amounts of crystals that would be needed to produce enough energy to...

Hi there, Had a fair bit of hoework my first day back with no answers. Would anyone mind looking over these to see if i did them correctly? Thank you for your time. http://img42.imageshack.us/img42/5117/46730937.jpg http://img35.imageshack.us/img35/4489/56478985.jpg...

I'm writing a book but my chemical knowledge is near non-existent and I need a TRUE scientific reason as to why warewolves would be 'allergic' to silver. I know I could make something up but I would like to have as much fact as I can when it comes to stuff like this. It'll help me stand out.

Homework Statement Why does the chemical reactivity increase as we go down in a group? Homework Equations none The Attempt at a Solution I know it has to do with the atomic radius... but I'm not sure :P

Hi there, i've already read some topics in this forum about the fermi-energy/chemical potential. I've also read the article "The chemical potential of an ideal intrinsic semiconductor" from Mark R. A. Shegelski which made the whole thing a little bit more clear to me. but there are some...

what's the difference? it looks like a chemical engineer and material scientist does the same thing

Homework Statement Do anyone know the product of: NaClO+Na_2SO_3 The thing is, while searching online, I found: Na_2SO_4+NaCl While the instructor had something along the line of (and he himself isn't sure of the answer, since he is not the one who wrote it): Cl_2+Na_2SO_4+H_2O Or...

Hey. Im currently doing a course in numerical analysis, and while most of the focus is on the mathematics side of things, the assignments are set in an engineering context. One of my assignments describes a beam that is "pin jointed" at both ends, is 1 meter long, and is subject to a 0.5 N/m...

Chemical Amount?? Hey guys, I'm looking for a little help with the whole concept of chemical amount. This question was posed during my intro chem lecture (assume a hydrogen atom's mass is 1 amu, and an oxygen atom's mass is 16 amu): How much oxygen does one need, to have the same number of...

Homework Statement Could someone verify if these are correct, my text does not provide answers and i have a test tom. Thank you very much. http://img251.imageshack.us/img251/9319/lastscanx.jpg http://img251.imageshack.us/img251/886/lastsc1an.jpg...

I was wondering how come when ever there's a question like aluminum reacts with bromine it is usually written like Al + Br2? or Potassium reacts with oxygen is K + O2? How do we know when there's 2 of them?? Is there like a special rule? Why isn't there K2 or Al2??

Just a quick question. Whats the name of the chemical that kills odors which come from decomposing bodies? Thanks in advance, fawk3s

Homework Statement Okay, a while ago, I did a lab that had me get glucose osazone (C18-H22-N4-O4). Now, I am trying to calculate the theoretical mass of the osazone. The chemical equations goes as follows: C6-H5-N2-H3*HCl + Na-C2-H3-O2*H2-O ------> C6-H5-N2-H3 + H-C2-H3-O2 + Na-Cl +...

Homework Statement I am to balance the following equation: Al(OH)41-(aq) + H2SO4(aq) ---> Al(OH)3(s) + H2O + SO42- The attempt at a solution Al(OH)41-(aq) + H2SO4(aq) ---> Al(OH)3(s) + 3/2H2O + SO42- The bolded part above is all I could add to the equation, but I now need to balance...

[b]1. Ok here it is, this is one monster of an equation that I have tried and TRIED to balance. hopefully somebody can give me a hand with this thing, thanks in advance [b]2. CaCO3 + Al2SiO5 ---> CaO + CO2 + Al2O3 + CaSiO4 [b]3. What can I say, I've tried repeatedly and can't...

I am trying to find the chemical composition for basic, college chemistry lab quality thermite. I saw that it was a white/grey powder substance. Trying to figure out what the exact chemical composition might be. :)