Recent content by joeyjo100

  1. J

    Why can't i see the milky way?

    i was walking down the road, looking up at the stars and i wondered why i didn't see more, and specifically why i couldn't see the miky way stretching across. i live in the city, so i guess the fainter stars will be blocked out by light pollution. But surely the light from a billion stars...
  2. J

    Spectral Lines: Wavelength & Frequency Explained

    what is a spectral line of a molecule? can this be used to work out the wavelength and frequency of the incoming light?
  3. J

    Spectrophotometry and Beer-Lamberts Law

    Homework Statement A molecule has a spectral line at 27319 cm-1 what is its wavelength? what is its frequency? Homework Equations A=εCl where A=absorbance, ε=molar extinction coefficient, C=concentration and l=path length The Attempt at a Solution thought about doing 1 over the...
  4. J

    Does weight affect speed on a water slide?

    I have just returned from a holiday in turkey, and the resort we stayed at had a water slide that ran into the pool. When sunbathing, I noticed that any children who attempted the water slide seemed to descend at at a slower rate than when a larger/fatter adult tried it. Now, I am firm in my...
  5. J

    Effect of Catalyst on Equilibrium & Rate Constant

    Can you have catalysts that only affect, say the forward reaction? Or a catalyst which affects the rate of the forward more than the reverse? I apologise in advance if I have broken any laws of the universe :/
  6. J

    What is the correct structure for transition metal complex ions?

    yeah. I forgot that I'd posted that, I've been in my own little revision world lately so things just keep coming and going. And in fact I just looked back at the reply in my last post. I do admit that it's a bit over my head, but I guess that in itself is an answer. It means that I don't need...
  7. J

    What is the correct structure for transition metal complex ions?

    well i would have guessed a tetrahedral shape for [CoCl4], just because there are 4 chloride ions, which would try and repel each other as much as possible. The tetrahedral shape has a bond angle of 109 degrees compared to 90 degrees for a square planar shape, so this allows the greatest...
  8. J

    What is the correct structure for transition metal complex ions?

    I'm getting myself muddled up, and don't know how to work out what the 3-d structure of transition metel complex ions. For example, the compound [CoCl4] has a Cobalt +2 ion surrounded by four chloride ions. I've seen two different structures for it. One is tetrahedral, like methane, the other...
  9. J

    Why Do Complex Ions with the Same Number of Ligands Form Different Shapes?

    I'm currently trying to cram knowledge of the transition metals into my head for a chemistry final exam, although i have come across a stumbling block when reading about the 3 dimensional shapes that complex ions form. My textbooks say that complex ion with 4 coordination bonds will form a...
  10. J

    What is the relationship between enthalpy of formation and temperature?

    Doesn't Kw change with temperature simply because the density of water changes with temperature. As far as my knowledge stretches, the constant of Kw at room temperature arises from the equilibrium of the auto ionisation of water. Because the concentration of water is always constant, this was...
  11. J

    What is the relationship between enthalpy of formation and temperature?

    I have been told that the hydrogen ion concentration of an acid in solution depends on temperature. What exactly is this relationship? Is there a formal equation that relates [H+] and temperature, as well as any other physical variables that may have an effect?
  12. J

    Medical Which Form of Radiation is Most Damaging to Human Cells: Alpha, Beta, or Gamma?

    Just been revising radiation for an upcoming exam, and was wondering which form of radiation, \alpha, \beta or \gamma is the worst to be exposed to? Ionising power decreases from alpha to gamma, but penetrating power increases from alpha to gamma. Which is more important when considering how...
  13. J

    Transition metal colours help

    For my a levels, I think I need to know the colours of each oxidation state of the transition metals, from scandium to zinc. Is there any easy way to remember each one?
  14. J

    What is the kinetic energy of an object traveling at the speed of light?

    When an object is traveling at the speed of light, c, what is its kinetic energy? Is it the objects mass multiplied by the speed of light squared, according to Einsteins special relativity? Or is it the objects mass multiplied by its velocity (speed of light) squared, divided by 2, according...
  15. J

    Charles' law and absolute zero

    According to Charles' law, volume decreases with temperature. Extrapolating down towards absolute zero, and the volume of the gas will be zero. How can this be possible? Surely any amount of gas will still have to take up some volume in space. Can multiple gas molecules really occupy zero volume?
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