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    May 2017
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  1. Scienuk

    Acids and Bases P1 Help!

    Thank you, But I didn't quite understand your answer for the first question, what I did to obtain it was convert pKw to Kw, square the value of Kw and then calculator the negative log of the answer to get to 7.27, but it seems impossible to do it without a calculator. If you can please explain why you divided the pKw by two, that'll be great.
  2. Scienuk

    Acids and Bases P1 Help!

    pKw for water at 10^oC = 14.54. What is the pH of pure water at this temperature? a) 6.73 b) 7.00 c) 7.27 d) 7.54 The answer is c, I fully understand how to get to this answer, however I don't know how to do it without a calculator due to the difficulty of the arithmetic involved. Which is correct for a weak acid, HA, with concentration 0.01 mol dm^-3 at 298K? a) [H^+] < 1x10^-2 b) pH < 2 c) [OH^-] < 1x10^-12 d) pOH > 12 The answer is A, why is that? isn't the concentration of H^+ exactly 0.01 mol dm^-3 as stated in the question? why is it less. Another question I have is whether the mixing of different acid/base indicators is included in the syllabus, if so, may someone please explain it? Thanks!
  3. Scienuk

    Kinetics help!

    May someone please answer the question and explain what is meant by the transition state and how you got to the answer, I have looked for this in my book but can't seem to find anything about it. Thanks!
  4. Scienuk

    Equilibrium and Energetics help!

    My thoughts exactly, thanks!
  5. Scienuk

    Equilibrium and Energetics help!

    By completion you mean favouring the forward reaction, I gather, correct me if I'm wrong. Also, where in the question is spontaneity mentioned? how exactly may it be related, I have an idea but am not sure, if you would elaborate on that please. Thanks!
  6. Scienuk

    Equilibrium and Energetics help!

    The answer is A, can someone explain how you got to the answer and the relation between temperature and equilibrium using the given equation? It doesn't seem to be mentioned in my book.
  7. Scienuk

    Acids and Bases P1 Help!

    Don't worry! the exam is on the 11th, more than a month left!
  8. Scienuk

    Acids and Bases P1 Help!

    They're HL, you're fine
  9. Scienuk

    Acids and Bases P1 Help!

    May anyone please answer these questions in detail? thank you! The answers are A and D, respectively.
  10. Scienuk

    Acids and Bases

    The answer is B; Can you fully explain the question and how it is solved, thanks!
  11. Scienuk

    Entropy help

    In your videos you say that the total entropy is equal to the entropy of the system + the entropy of the surroundings, so is it the same as saying the total entropy is equal to the entropy of the reaction + the entropy of the surroundings?
  12. Scienuk

    Entropy help

    Is the entropy of the system the same as the entropy of the reaction?
  13. Scienuk

    Entropy P2 help

    Forgot to do that, thanks.
  14. Scienuk

    Entropy P2 help

    For part (c) I got 335 J K^- mol^- which is correct according to the mark scheme, however when I tried to see if I get the same answer when using the standard entropy values (products minus reactants) provided in the table I get 70.8 J K^-1 mol^- which is a completely different answer, why is that so?
  15. Scienuk

    Energetics help

    Thank you! but why did you decide to cancel out the O2s from both reactions, any specific reason?

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