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  1. 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...
  2. 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.
  3. 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...
  4. wizzkids

    Polariser

    Ahh yes, good point. therefore is impossible to transmit 60% of the original intensity.
  5. 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.
  6. 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...
  7. 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...
  8. 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)...
  9. 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...
  10. 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...
  11. 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...
  12. 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...
  13. 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?
  14. wizzkids

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

    Have you done all the examples in Copeland's "Engineering Studies" volume 2?
  15. wizzkids

    Generic response for collision theory questions

    For a full discussion of Collision Theory and its influence of the equilibrium constant, please see this previous post. Equilibrium Constant and Temperature
  16. wizzkids

    Physics HSC 2021

    Simple. Apply Lenz's Law. The eddy currents in the copper block will respond in such a manner as to oppose the change that caused it. The cause is the relative motion of the magnet. Therefore the induced eddy currents will try to reduce the relative motion of the magnet. If the copper block was...
  17. wizzkids

    Dissolution

    I dare you to actually try to saturate a solution of sodium hydroxide, see if you can do it. But be VERY careful, there will be a lot of heat generated. It will look like a slushie with steam coming off, and as soon as it cools down, it will turn back to solid.
  18. wizzkids

    Dissolution

    This is a stupid question in my opinion. For sodium hydroxide, the answer is "No", it is not an equilibrium reaction. Sodium hydroxide is deliquescent, the solid spontaneously hydrates when ever water is around. There is a large ΔH and large ΔG for this reaction, and you can feel the solid...
  19. wizzkids

    Book review....?

    The reviewers comments on Eureka Publications website are very favourable. The price of $45 seems very reasonable as textbooks go, and it's printed in colour. It's not a complete guide to the whole Year 12 syllabus, but if you can afford it , why not?
  20. wizzkids

    Chem modules

    Unquestionably, it is Module 7 Organic Chemistry that is the most difficult. The Year 12 syllabus steadily ramps up in terms of difficulty, from module 5 to 6, and then you hit module 7 and it goes to another level entirely. You have to start understanding the subtlety of shapes of molecules...
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