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dorianb

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  • Gender
    Male
  • Exams
    May 2015
  • Country
    Norway
  1. Sure thing - what subjects are you thinking of?
  2. Wrote heat loss, and proper insulation by use of bomb calorimeter as improvement
  3. Well I got 22%, but used the wrong delta T, so :/ bot for the conc I got something like 0.0833..
  4. the same here What Did you get as the concentration?
  5. Looks about right.. I didnt extrapolate, and used the volume where the temperature was the highest - so 30 cm^3...
  6. I said the same thing. 107 for one and <120 and<180 for the other one.both had a lone pair. What did you writr for the question were they asked about the covalent bond between hydrogen and carbon? Shared pair of electrons closer attracted to carbon due to its higher electro negativity though I squeezed that last bit in right at the end, may not get the mark. Regarding the percentage error, I got 60 but I used 0.05 not 0.025 mol to work out delta H (the first of my silly mistakes!!) I believe the correct answer is around 20%. For the delta T I wrote 6 degrees, which I only noticed the last 5 min. But with that I got 22%, so 20% sounds about right... Hopefully I only lose the one point on the delta T but get the points with ECF I got Del T = 5.2 C? Did you extrapolate the line of best fit from the max temperature on to the y axis and use that temperature reading or directly use the highest reading on the graph (and then subtracting from the same initial reading)? Also what were your major sources of error? I wrote heat loss to the environment, and use of a styrofoam cup to minimize heat loss. I wrote 6, but you are right, it was 5.2, but only noticed that right before the end... And I used 30 cm^3 as the volume of HCl, as that was when the temperature was at its highest - I didnt get what they wanted us to do with the line
  7. Same here man, thought it was just H, not H2.... Silly mistake
  8. I said the same thing. 107 for one and <120 and<180 for the other one.both had a lone pair. What did you writr for the question were they asked about the covalent bond between hydrogen and carbon? Shared pair of electrons closer attracted to carbon due to its higher electro negativity though I squeezed that last bit in right at the end, may not get the mark. Regarding the percentage error, I got 60 but I used 0.05 not 0.025 mol to work out delta H (the first of my silly mistakes!!) I believe the correct answer is around 20%. For the delta T I wrote 6 degrees, which I only noticed the last 5 min. But with that I got 22%, so 20% sounds about right... Hopefully I only lose the one point on the delta T but get the points with ECF
  9. I said the same thing. 107 for one and <120 and<180 for the other one.both had a lone pair. What did you writr for the question were they asked about the covalent bond between hydrogen and carbon? For the SF4 I wrote see saw, as it has 5 charge centres, 1 non-bonded, and angles of 117, 90 and 180
  10. Wasnt it something like the electrolysis of aqueous H2SO4 and CuSO4? I just remember choosing that the same amount of O2 was produced
  11. Econ. Always econ. I take history, and I cant express how dearly I wish I took econ...
  12. But why would you subtract 10? I mean, the goal is to have a fair game, meaning that the net gain is 0. Hence, if you pay 10 and have an expected value of 10, problem solved... I don't understand why you'd subtract either, but this is my friend told me. She did it the same way I did but apparently it's wrong. And how do you know it is wrong?
  13. It was ( lnx^2 / 2 ) But like... that was something like integration by parts? yes i guess, it was quite hard though, i missed out on the (/2) part of the answer because I didn't notice. I checked the answer after the exam and it was (lnx^2 / 2) Did you use substitution method? I used the chain rule in reverse... Because lnx/x is simplified to lnx * 1/x, and since the derivative of lnx is 1/x the 1/x must have come from the differentiation of lnx. Hence, if you take 1/2(lnx)^2, the chain rule will give you lnx/x... at least how I did it..
  14. But why would you subtract 10? I mean, the goal is to have a fair game, meaning that the net gain is 0. Hence, if you pay 10 and have an expected value of 10, problem solved...
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