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  1. Mathemagical

    Chemistry P34

    Draw tables up before carrying out the actual experiments. This will save you time as you do not have to copy your results again. Try to allocate a specific amount of time to each question, e.g. 45 minutes for titration, 40 minutes for qualitative analysis, etc. Wash apparatus before using them...
  2. Mathemagical

    Physics: Post your doubts here!

    Diagram 2 shows the zero error of the instrument. To calculate the accurate reading, use the formula: Actual reading - zero error.
  3. Mathemagical

    Physics: Post your doubts here!

    The most energetic molecules - those which possess the most kinetic energy - have sufficient energy to break the liquid bonds and escape into the atmosphere. This leaves behind the less energetic molecules, hence reducing the average kinetic energy of the remaining molecules.
  4. Mathemagical

    Chemistry paper 34 as level practical guess papers

    I have finished the Chemistry Paper 33 on May 7, and I will share some information on the paper with all of you. Question 1: A normal titration question, but this time the indicator used was bromothymol blue, the first time I've seen it appear in a practical paper. I performed a rough...
  5. Mathemagical

    Chemistry: Post your doubts here!

    It burns readily, so there will be a high concentration of CO2 in the equilibrium mixture. Therefore, applying the formula for equilibrium constant, we can deduce that the value is likely to be high.
  6. Mathemagical

    Chemistry: Post your doubts here!

    Yes, I suppose so :)
  7. Mathemagical

    Chemistry: Post your doubts here!

    Yes, I suppose so :)
  8. Mathemagical

    Chemistry: Post your doubts here!

    That's exactly the same. Recall the definition of combustion and you should realise that the arrow should be pointing toward the product of combustion.
  9. Mathemagical

    Chemistry: Post your doubts here!

    The change from B to A involves atomisation, which takes in energy and therefore is endothermic. Thus, A has a higher energy level than B.
  10. Mathemagical

    Chemistry: Post your doubts here!

    I2 is a molecule, and covalent bonds are found in each I-I molecule. In addition to that, in between the I-I molecules, there are weak van der Waals forces.
  11. Mathemagical

    Chemistry: Post your doubts here!

    This is a tricky one. The question asks how many product molecules have the ketone functional group, not how many ketone functional groups there are. Therefore, the 2 parts on either side will form one molecule each with 2 ketone groups. Add that to the 4 in the middle and you have 6.
  12. Mathemagical

    Chemistry: Post your doubts here!

    For enthalpy change of formation, the arrow must point from the individual constituents to the final product. If the arrow is in the opposite direction, the enthalpy change will have the same magnitude but opposite direction.
  13. Mathemagical

    Chemistry: Post your doubts here!

    Esters are generally insoluble in water. Visit this link for more information: http://tinyurl.com/m7jksj It cannot be ethanoic acid because it reacts with PCl5 to form acyl chlorides.
  14. Mathemagical

    Chemistry: Post your doubts here!

    2H₂ + O₂ --> 2H₂O It would form water.
  15. Mathemagical

    Chemistry: Post your doubts here!

    Yes, only by trial and error :)
  16. Mathemagical

    Chemistry: Post your doubts here!

    In C and D, the dipoles sort of "cancel out" each other so the overall dipole will not be as large as the one in B.
  17. Mathemagical

    Chemistry: Post your doubts here!

    This requires a bit of trial and error. The answer is D.
  18. Mathemagical

    Chemistry: Post your doubts here!

    No, it would not be correct. The signs + and - are very important in Hess Law reactions, and it is important to keep them in mind while attempting questions of this sort.
  19. Mathemagical

    Chemistry: Post your doubts here!

    The answer is A. From the diagram and the arrow showing the enthalpy change of formation, we can conclude that the bottommost layer is CO2(g). Thus, the second from bottom level has to be Option C, which shows the elements in their standard states. Working our way upwards, we can see that the...
  20. Mathemagical

    Physics, Chemistry and Biology: Post your doubts here!

    Visit the following websites for information on half-equations: http://tinyurl.com/nzcj9pg Advanced-->http://tinyurl.com/e493f Hope this helps!
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