1. CCMarie

    I Entropy and coding

    For {pi}i=1,n being the probability distribution, I want to show that a Huffman reduction cannot be decreasing, and I reached a point where I need to show that q+H(p1,...,pn-s,q) ≥ H(p1,...,pn), where q = pn-s+1 + ... + pn and s is chosen such that: 2 ≤ s ≤ m (m≥n) and s = n (mod(m-1)) where...
  2. K

    Redox titration

    Cl2(g) + 2I–(aq) -->I2(aq) + 2Cl–(aq) (reaction 1) [2S2O3^(2-)(aq) + I2(aq) --> S4O6(2-)(aq) + 2I–(aq) (reaction 2) Why isn't n(I2)(reaction 2)=2n(S2O3^(2-))(reaction 2). I don't see why this is wrong. <edit: remove size and italics>
  3. H

    A Interdependent Recursive Equations

    Hi, I have a system that I am trying so solve in terms of m, and have two recursive equations: The problem for me is that each recursion is dependent on the value from the other! I know that they are both solvable, however I have no idea what approach I could take to express each only in...
  4. A

    Are the terminals of a Battery neutral?

    So I've been learning how batteries work. What I learned is that a battery consists of 2 pieces of metal both with different electronegativities. These metals react with an electrolyte. One metal (called the anode) is oxidized and has its electrons removed, leaving behind a positive ion which...
  5. alphaj

    Is this a redox reaction?

    Quick note: Sorry for dominating the homework help board, guys! But, I wanted to say thank you to everyone who replies to my excessive questions. This forum's input has become integral to me as I am in a position now where I can't go to my teacher for help because of the logistics of commuting...
  6. E

    Calculate Pressure Drop through Expansion/Reduction for Gas

    Something that routinely comes up as a problem at work is when we size flow projects for piping systems. We calculate pressure drop across a length of fixed diameter for compressible gasses, but we do not calculate pressure changes through an expansion or contraction with gas (for example...
  7. Wrichik Basu

    What is the difference between valence factor and n-factor?

    What is the difference between valence factor and n-factor for oxidants and reductants? Take ##H_2O_2## as an example. What is the difference between the n-factor and valence factor for this compound? Also, how do I find the n-factor for any oxidant or reductant?
  8. M

    A block diagram reduction

    I would like to ask why cannot I think G5 in series with G3(G4+G6G7) and then after muliplying them why I cannot think of G5*G3(G4+G6G7) in parallel to G2 so sum G2 and G5*G3(G4+G6G7) ? Thank you.
  9. A

    Automotive New In tube end forming practices -- Can I downsize and then upsize a pipe end?

    In tube end forming practices, is it possible to first reduce the diameter of the pipe (tube 0.9mm thick) and then expand it, at the same end, by about 1mm in total, with a transistion radius of 8mm ? Please see attached image. Though it might be exaggerated, but the image should suffice. I want...
  10. S

    How can I plate Cu at very low currents

    Hello, I have a silicon wafer with a 50nm layer of copper sputtered on it. I coated it with a 1µm of positive photo resist and patterned it with a UV laser stepper. Then I developed it and washed it thoroughly. The pattern has a surface area which measures appx 1300µm x 8µm. What I want to do...
  11. G

    Proof of NP-completeness via reduction

    1. Homework Statement You are given some undirected graph G = (V, E), along with a set S which consists of 0 or more pairs of G's edges. As an example, a complete graph on 3 vertices (a triangle, basically) would be described as follows: G = (V, E) = ({v1, v2, v3}, {v1v2, v2v3, v1v3}). A set S...
  12. Stephanus

    Methane from sugar

    Dear PF Forum, Can anyone help me? I'd like to know what is the reaction that produces methane from sugar? I believe it's reduction. This is sugar oxydation: C6H12O6 + 6O2 -> 6CO2 + 6H2O What is the reaction to produce methane from glucose? C6H12O6 + ??? -> CH4 + ??? And please if you would be...
  13. Stephanus

    Percentage of hydrocarbons in living organism

    Dear PF Forum, I'm interested in how much energy our organic waste contain. I have read this article Elements composition of plants The elements composition of human body (and animal?) and plants resemble. Bacteria has slightly...
  14. chad kimsey

    Strong reduction of organic acid group

    I've been thumbing back through my organic synthesis book to try and remember how to reduce a carboxylic functional group. I know how to do partial reduction to primary alcohols, or create aldehydes and or acyl halides. But isn't there a way to completely reduce it all the way to a hydrocarbon...
  15. C

    Deflection in a Cantilever beam

    Hello, i was looking for ways i can reduce the deflection in the cantilever beam whose one end is fixed and load is applied at the free end. Few i thought of was, 1- Reducing the length of the beam 2- Increasing the modulus of elasticity of the beam 3- ?? 4- ...
  16. N

    How do I calculate the cell potential?

    < Mentor Note -- thread moved to HH from the technical chemistryforum, so no HH Template is shown > I was given this problem: A voltaic sell uses the reaction 4Fe3+ + H2 --> 2Fe2+ +2H+. Find the cell potential when [Fe3+]=1.50 M, PH2=.50 atm, and [Fe2+]=.00100 M and the pH of both anode and...
  17. M

    Simple Symplectic Reduction Example

    1. Homework Statement I'm struggling to perform a symplectic reduction and don't really understand the process in general. I have a fairly solid understanding of differential equations but am just starting to explore differential geometry. Hopefully somebody will be able to walk me through this...
  18. Elvis 123456789

    Is this a Redox Reaction?

    1. Homework Statement Determine the oxidizing agent, reducing agent, element oxidized, element reduced, # of electrons lost per atom, and # of electrons gained per atom. State if the reaction is not redox. 3FeCl2(aq) ------> 2FeCl3(aq) + Fe(s) 2. Homework Equations 3. The Attempt at a...
  19. AdityaDev

    Basicity of hydrides

    I am confused with the statement given by a web site ( "Size. When comparing atoms within the same group of the periodic table, the larger the atom the weaker the H-X bond and the lower the electron density making it a weaker...
  20. AdityaDev

    Reduction of quaternary ammonium salt

    I am confused with the reduction of quaternary ammonium salt. ##Ph-CH_2-CH_2-N^+Me_3## on reduction with Zn-Hg in HCl will not work. The -NMe3 is not disturbed(given in my text). But why? Also the text says On reduction with LiAlH4 or NaBH4, -NMe3 would be disturbed. what would be the product...
  21. C

    Validity of the Pauling Scale of Electronegativity?

    I propose the Pauling Scale is not valid in all circumstances, and other scales of electronegativity would do better to predict the behavior of electron density in molecules: Electronegativity seems to be poorly defined for such a widely used chemical property: a 'tendency' of an atom or...