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BedokFunland JC's A Level H2 Chemistry Qns (Part 2)

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    H2 Chemistry @ BedokFunland JC (near VJC & TJC)
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    • A 2017 BedokFunland JC Original H2 Chemistry Challenge, adapted from a Singapore-Cambridge A Level Exam Qn.

      Explain why, despite the Br-Br bond being weaker than the Cl-Cl bond, the rate of reaction between chlorine and phosphorus is faster than the rate of reaction between bromine and phosphorus (assuming the same allotrope of phosphorus is used, and assuming the same state or phase for both halogens).

    • Originally posted by jyjyjy:

      JJC P2 Q1(e) why is it that even though reaction is independant of [I2], when [I2] is halved, time is halved? wouldn't that be first order?

      Q5(c)(iii) How does this mechanism look like? Is it possible for the Br- from step 1 to attack instead?

      P3 Q1(b)(ii) Why does the answer state that when the reaction just becomes feasible G=0? Isn't the reaction feasible when G<0? When G=0 isn't it just at equilibrium?


      P2 Q1e) If I2 was 1st order, then the half-life would be constant, ie. no change. Since I2 is a 0th order reactant, half-life is halved when molarity is halved.

      P2 Q5ciii) SN1. If the leaving group Br- attacked back, then you would end up with the original reactant, ie. no net reaction occurred.

      P3 Q1(b)(ii) Yes you're right, but what exact value are you going to substitute in for delta G? -1? -0.1? -0.01? -0.001? So just use delta G = 0 first, then state that for the reaction to be thermodynamically feasible, the temperature needs to be higher than 958K (ie. take initiative to improve on the given mark scheme answer, when answering such questions in the A levels).

    • Originally posted by Earthcosmic2:


      Every year ? You mean ever since you ORD'd, you have been taking and re-taking A-Levels every year ? Sounds fun. lol. I want to re-take my A-Level is cos of interest in the subjects like Physics and Maths. Not sure whether I should take the whole combi or not or just the subjects I am passionate in. Sigh ....


      Every year since 2012. Leading by Example. I'm the only H2 Chemistry private tutor in Singapore who does this.

      http://infinity.usanethosting.com/Tuition/#A_Level_Results

      Since you're taking A levels out of interest, not out of necessity for University admission, then just take the subjects you're interested in and can self-study for.

      To self-study, you can use online resources such as OwlCove.sg (local), TickNinja (local), and of course, internationally acclaimed Khan Academy (international), by Salman Khan, the man who taught himself hundreds of subjects across all levels, and now teach billions of people online for free.

    • Citrus fruits, which include oranges, lemons, limes, pomelos and grapefruits, may have potentially deadly interactions with your Medicines.

      image

      https://en.wikipedia.org/wiki/Grapefruit%E2%80%93drug_interactions

      To skip the biochemical-genetic-medical explanations on the whys and hows, go straight to the list of Medicines that may interact with the chemical compounds in Citrus fruits :

      https://en.wikipedia.org/wiki/Grapefruit%E2%80%93drug_interactions#Affected_drugs

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