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Everything posted by DeanK2

  1. I have done the particle in a sphere with QM, but am trying to contrast it with the classical description.
  2. I would like to set up a statistcal equation to describe the probabiliity of where a particle can be found in a sphere of zero potential, and the collisions betweeen the wall and particle is perefctly elastic.
  3. The three most abundant elements: 1.) Hydrogen 2.) Helium 3.) Lithium (universe)
  4. Electronegativity is the ability of an atom to attract a pair of electrons in a covalent bond. The nuclear charge and the atomic radius determine the electronegativity - the larger the nuclear charge, the more it will attract a bonding pair of electrons. The smaller the atomic radius, the greater the attraction between the nucleus and the bond electrons. On descending a group, the effective nuclear charge on an atom remains the same, but the size increases. Therefore the top member is more electronegitve, as it is smaller and attracts the bonding electrons more. Therefore, an electronegative atom would not be readily oxidised. Therefore an electronegative metal would be low down in the electromotive series. The electromotive series begins with the metal most easily oxidized, i.e., the metal with the greatest electron-donating tendency, and ends with the metal least easily oxidized. The tendency to be oxidized is not an absolute quantity; it can only be compared with the tendency of some other substance to be oxidized. In practice, the tendency to be oxidized, called the oxidation potential and expressed in volts, is measured relative to a standard hydrogen electrode, which is arbitrarily assigned an oxidation potential of zero. ELECTROMOTIVE HAS NOTHING TO DO WITH ELECTRONEGATIVITY FOR A REFERENCE OF VALUES: BUT EACH CAN BE EXPRESSED BY EACH OTHERS DEFINITION.
  5. Enviroment? Sealed? If so, you can phosphorous to remove the oxygen - it will not react with water or corrode stainless steel. Unfortunately problematic element - reacts vicously and spontaneously with air - have not actuallly handled it myself so revise safety. Fire. Oxidised to [math]P_{4}O_{10}[/math].
  6. Laminar flow - imagine a Liebig condenser http://www.efm.leeds.ac.uk/CIVE/CIVE1400/Section4/laminar_turbulent.htm provides simple example for equation.
  7. DeanK2

    without trig

    [math]BDC=180-8x[/math] [math]ABD=180-12x[/math] [math]0<x< 15[/math] [math]20x+ABD+BDC=360; =>...ABD+BDC > 60...if...0<x<15[/math] With the limits above, x can be found. A simple logarithm would suffice.
  8. The above is sufficient, yet also the root itself must be differentiable.
  9. [math]x^4=x^2y-y^3[/math]; implicit differrentiation and the product rule must be applied. Solve as stated.
  10. Wiles proof that [math]x^n+y^n=z^n, n>2 --> xyz=0[/math] Lebiniz and his most elegant equation [math]pi/4=1-(1/3)+(1/5)-(1/7)....[/math]
  11. Revise phase equilibria and Raoults law. [math]P=P^ym[/math] P is the vapour pressure of the solution, [math]P^y[/math]=vapour pressure of the pure solvent [math]m[/math]=mole fraction of solvent in the solution. Use [math]pV=nRT[/math] to find kelvin.
  12. Not entirely sure that the question would contain the words incomplete dominance as it does not exist. The actual term is co-dominance - extremely important this is used, as in a question; the use of incomplete would loose all marks. Co-dominance is the term used to describe the way two DIFFERENT alleles are expressed in the phenotype of an organism. Consider these crosses in a punnet square: R-dominant, r – recessive R produces white flowers. r results in blue flowers r R R Rr RR r rr Rr It is clear that the genotype with a capital R would have white flowers. Approximately 3:1 would have white: blue flowers. The punnet tables are not easy to show, but top row of each one should be moved over by a place. Now, in co-dominance, there is actually no dominance. Both alleles are equally expressed: r R R Rr RR r rr Rr So, RR would be white, and rr would be blue. Rr would be a light blue - because neither allele is dominant over the other, the heterozygous genotype has its own phenotype. However, since the original phenotype has been unaltered and remains, they still obey Mendel's law of segregation. It is only the phenotype that appears to have undergone "incomplete dominance", and this is a common mistake. Co-dominance affects blood groups - that is why the AB group can be present - the A or B allele is not dominant, so both antigens are produced.
  13. The later questions require a slight knowledge in the dihybrid principle (Mendel) and co -dominance. If you need an explanation of both, with punnet squares, simply post.
  14. This is correct and balanced: CH3(CH2)2CH2OH + 6O2 ------------> 4CO2 + 5H2O
  15. To obtain sulfur, redox reaction with KI can be undertaken: 1.)KI + H2SO4 ---------> KHSO4 + HI 2.)2HI + H2SO4 -------> I2 + SO2 + 2H2O 3.)6HI + H2SO4 -------> 3I2 + S + 4H2O 4.)8HI + H2SO4 -------> 4I2 + H2S + 4H2O To obtain sulfur from SO2 and H2S, a chemical scrubber must be used - costly!!!
  16. The quicklime would most certainably be availbale from the shell, but the amount of eggs needed is probably ten times what the supermarket stacks (for a respectable amount of cement). However, it would be straightforward to purify, once obtained.
  17. Lewis structures will partially explain the bonding. It is extremely useful, but does not work all the time. This does not mean that it should be cast aside though. It is adequate for most molecules. Fortunately for ions, or an ionic compound, the oxidation number is just the actual ionic charge (for that element - remember a compound has an oxidation stae of zero unless staed). Oxxidation numbers can also be used for covalently bonded molecules - group 1 elements will always have an oxidation state of 1, and flourine will always have an oidation number of -1, etc, just a few exceptions. A knowledge of molecular orbital theory accounts for bonding in more detail. However, hybridisation crushes the problem with a lewis structure for certain molecules. For example, a lewis structure of the cyanate ion CNO- is shown as a stucture with either a negaive nitrogen, or a negative oxygen - this NEVER OCCURRS. The molecule will be more simply a mixture of the two, but never one or the other. This is why hybridisation is extremely useful, as it shows how electrons are distributed between the bonding orbitals orbitals of the cyanate ion, with no distinct "contributor" structure.
  18. Was your doctorate in maths? If so, there will be little in the course that will be a real concern - i.e. the hardest problem may be nth order differential equations, multivariable calculus, fourier series, lambda calculus and possibly numerical solutions to PDE's.
  19. Are you in dire need of an answer, or simply curious? Hopefully it is the latter as the neccesary substances with the properties that hermanntrude has mentioned will be almost impossible to find.
  20. Aside from the actual seperation of chemicals in the air, there are many man made contaminants present, especially at industrialized areas. They will include carbon monoxide. Collect the fumes from a car in a sealed container. In this container, add water, and heat. This is NOT how the majority of acid rain is formed (oxides of nitrogen and sulfur take part in a series of reactions to produce nitric acid and sulfuric acid respectively), and open the container carefully. Add litmus paper to this solution containing disolved carbon monoxide. An interesting demonstration of an interesting molecule undergoing an interesting reaction
  21. Global Warming The Complete Briefing, 3rd edition contains more information than several books combined, and if interested, should certainly be bought as it is contains exceptionally good information - yet it has by far one of the most uninteresting reading formats.
  22. The science behind genetic modification is extremely straightforward, and it is of no wonder that a prospect with such value has been drawn away from research. Although a relatively new technology, GM crops are extremely controversial. This is common, and to say the least, genetic modification has become extremely commercialised. They buy the right to have little opposition or stringent guidelines proposed by the government. The government in America sees no need for compulsory labelling of genetically modified food, in supermarkets, greatly increasing the testing size of GM foods and endangering many lives, as the potential risks are unknown. The health of the public is put at risk to increase the companies’ profits considerably – an activity of great moral concern. It is of a personal matter to the consumer, and evident from the poll, many of the scientifically active members of the population - in this forum as well - underestand the implications of genetic modification. On the horizon are bananas that produce human vaccines against infectious diseases such as hepatitis B; fish that mature more quickly; cows that are resistant to bovine spongiform encephalopathy (mad cow disease); fruit and nut trees that yield years earlier, and plants that produce new plastics with unique properties Genetic modification needs to remain active, as a promising and lucrative enterprise for the future solution to the food distribution problem.
  23. Whatever happened to the water fuelled engine? The hydrogen and oxygen are obtained by electrolysis of water. However, this reaction requires a great amount of enrgy - the covalent bonds are strong. It is impractical to start electrolysis in the car. There would be large power stations that would do this, and the hydrogen would be transported to the cars. Yes, the oxygen from these large electrolysis "power" plants would be released into the air. So far, this seems to be understood by you. However, it is a common misconception that hydrogen itself will be combusted (which would rightly mean that the exhaust would, after combustion, expel water vapour). There are new fuel cells that are apparently far more efficient than combustion. The hydrogen is chemically reacted with oxygen, among other chemicals, in the fuel cell. Therefore, the oxygen is not expelled, and both would be required to produce electricity.
  24. The correct name of this compound is 3,5,7-trihydroxy-2-(3,4,5-trihydroxycyclohexyl)-octahydrochromen-4-one. Yojoe knows his nomenclature
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