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  1. wizzkids

    polarisation

    No you're not. You're doing just fine. Just make sure you read all parts of the question, and underline the important facts.
  2. wizzkids

    polarisation

    In the original post, it says Io is the intensity after leaving polarising filter #1. Therefore Malus' Law only applies to the interaction between polarizing filter #2 and filter #3. Therefore the intensity after leaving filter #3 varies from zero to 0.5 Io.
  3. wizzkids

    polarisation

    This is a common misconception, but the influence of the first polarizing filter over the third polarizing filter (or the second analyser if you want to refer to it that) is irrelevant once you introduce the middle polarising filter. I have done this experiment many times in class with three...
  4. wizzkids

    polarisation

    Yes, the intensity of the light will halve after passing through the first filter, but it will not halve after passing through the second filter. The law about halving the intensity only applies to unpolarised light that has passed through an ideal polarising filter. Once the light has become...
  5. wizzkids

    mass spec isotopes

    Regarding H, C and O. Look at those values for abundance. There is only one dominant isotope, the other isotope is totally insignificant for the mass spectrum, so no need to memorise those ones. Regarding those other elements, as part of your general knowledge in Chemistry, you should be aware...
  6. wizzkids

    QATS Trial 2019

    First, we must assume that the wave fronts are drawn as if they are synchronous, that is they are generated at the same times. Next we look for places where the first wavefront from the left-hand source intersects with the third wavefront from the right-hand source, and draw a point. This is a...
  7. wizzkids

    NH3

    H2O donates a proton to NH3. The Bronsted-Lowry model of a base is any substance that is a proton acceptor.
  8. wizzkids

    QATS Trial 2019

    Obviously the wave fronts are separated the wavelength λ. Place numbers on the wave fronts radiating out from each source. Maximum constructive interference occurs where wave crests coincide. There are going to be multiple points where the wave fronts are out-of-phase by exactly 2λ. The points...
  9. wizzkids

    Summary of dispersion forces in hydrocarbons

    Yes, you nailed it. The only thing that we should add is the shape factor - the dispersion forces increase as the chain length increases, and they fall as the degree of branching increases hence the molecule tends to become more spherical in shape.
  10. wizzkids

    can someone please explain complexation

    Yes, there is a lot of jargon around this topic. Complexation, as far as the HSC Chemistry course is concerned, refers to certain metallic cations that can become surrounded by a shell containing 4 or 6 negatively charged anions, or polar molecules with their delta-negative bits pointing towards...
  11. wizzkids

    Polariser

    Ahh yes, good point. therefore is impossible to transmit 60% of the original intensity.
  12. wizzkids

    Polariser

    Then we apply Malus' Law and make θ the subject of the equation. θ = cos-1( √0.6) which is about 39 degrees.
  13. wizzkids

    Polariser

    The question is supposed to be examining Malus' Law. If you just apply the equation I/Io=cos2θ = 0.5 However there is a trap buried inside this question that probably makes it invalid. Unpolarised light, presumably from the Sun, has reflected off the ocean and during this reflection it becomes...
  14. wizzkids

    calibration

    There are many ways to perform this calculation; here is an alternative to @Luukas.2 Determine the mass factions of Cu and Cl in the compound CuCl2. This compound is 63.5 amu of Cu and 70.9 amu of Cl, so 47.2% Cu and 52.8% Cl by weight. Now let's look at Solution 2. Reading off the graph, and...
  15. wizzkids

    Forces Q

    The other factor to consider is centripetal acceleration. The skateboarder is not just falling vertically under gravity, but executing a circular path. However, the velocity of the skateboarder is zero at point A and also diametrically opposite point A (maybe we should refer to as point C)...
  16. wizzkids

    Trial Q

    To answer this question, you need to go back to Year 11 content from Waves and Thermodynamics. To achieve a high electromagnetic field around a wire, you need to achieve resonance, and a standing wave represents resonance. Therefore the length of the wire is related to the positions of nodes and...
  17. wizzkids

    UV vis

    Agree with @Unovan this is a weirdly worded set of answers. UV-Vis Spectroscopy relies on photons that are more energetic than infrared, so these photons are not absorbed in rotation, translation or stretching of bonds. These photons are absorbed in electron energy transitions. (A) is sort-of...
  18. wizzkids

    Primary amines

    All hydrogen bonds are not the same. We can assign a bond enthalpy to the hydrogen bonds, and typical enthalpies can range from -1 or -2 kJ/mol up to as much as -25 kJ/mol. You can talk about the potential for more hydrogen bonding between molecules. The difference between amide and carboxylic...
  19. wizzkids

    Primary amines

    This is not a valid question. Perhaps you have forgotten the fundamental nature of hydrogen bonding. Hydrogen bonds only last for between one to ten picoseconds. They are highly transitory and subject to statistical distribution and therefore cannot be counted as such. All we can say is there is...
  20. wizzkids

    Where can I find a good source for topic specific calculation questions

    Theory means calculations, so I don't understand the distinction you are making. Perhaps you mean qualitative versus quantitative questions. What about pages 69 to 73 in Copeland. Have you done all of those problems and got them right?
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