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  1. xIshtar

    all physics unit 3 ! doubts , notes , discussion in here =p !

    Basically planning practicals, graphs and calculations :P
  2. xIshtar

    chemistry unit 3 !!! discussion in here !! =p

    Yeah, I saw :P I had SO4 in my head for some reason, my apologies :P
  3. xIshtar

    chemistry unit 3 !!! discussion in here !! =p

    To test for sulphate ions you add barium chloride after acidifying, and get a white ppt. And oh dear, I read it wrong :/ Yes, that is a test for SO2 :P
  4. xIshtar

    chemistry unit 3 !!! discussion in here !! =p

    The test for SO3 is potassium dichromate, which changes from orange to green.
  5. xIshtar

    chemistry unit 3 !!! discussion in here !! =p

    If it is SO3 2- Then, S is +4 And thus it has the same charge as that in SO2, as sulphur is also +4 there. Basically, just make sure you look at charges and ions, to be certain that is oxidised :) How is everyone feeling?
  6. xIshtar

    chemistry unit 3 !!! discussion in here !! =p

    2 Identical answers, just with different focuses on the reaction. And we're both right so :p H2SO4 is reduced by potassium dichromate to form SO2 Look at the oxidation numbers, +6 to +4. In SO3 Sulphur is +6 and in SO2 it is +4. By OILRIG, electrons have been gained, so it has been...
  7. xIshtar

    chemistry unit 3 !!! discussion in here !! =p

    Steamy gas, purple vapour, a yellow solid all produced in a vigorous reaction.
  8. xIshtar

    Edexcel January 2012 Question Papers & Mark Schemes (ALL GCE)

    Thanks a bunch for this :D
  9. xIshtar

    Unit 1 edexcel chemistry! :(

    Not sure what you mean really?
  10. xIshtar

    chemistry unit 3 !!! discussion in here !! =p

    That depends if it is acidified or not. If it slightly acidified it will go from purple to colourless as oxidation takes place. But if it is slightly alkaline it will go from purple to a browny colour.
  11. xIshtar

    chemistry unit 3 !!! discussion in here !! =p

    I agree completely, and I almost wrote all that out myself :P But I thought that you should shake just before you make it up to the mark, as when you dissolve it in the solvent, can't it cause changes in volume which would then lead to inaccuracies?
  12. xIshtar

    chemistry unit 3 !!! discussion in here !! =p

    Thats making a standard solution I believe. You have to use a volumetric flask and such.
  13. xIshtar

    chemistry unit 3 !!! discussion in here !! =p

    Heat enthalpy depends on the reaction, as someone said, temperature rise, then the energy value will be positive. Temperature fall and it will be negative. Decanting is when you pour off some of the liquid on the top, to try and leave only the solid behind.
  14. xIshtar

    Chemistry paper 31 (NEW)

    And for the hard moles one, I wrote that the molar ratio between the metals and the hydrogen was the same with A and C, but with B it had a higher ratio, meaning a higher amount of moles and thus a large volume was produced :D
  15. xIshtar

    Chemistry paper 31 (NEW)

    But for the second one I wrote the same thing.. I wrote for the chlorine one, a colour change from colourless to black/dark brown, and a colour change to yellowy brown. I wrote that the Selium was the reductant, I though about writing a base, but I've only ever seen a question asking you to...
  16. xIshtar

    Chemistry paper 31 (NEW)

    Uhmm, I put the redox one was the second carbonate reaction. As zinc was reduced to zinc iodide, and the H ion was oxidised to water..
  17. xIshtar

    chemistry mark expectations

    My expectations: p1 36-38/40 p3 65-75/80 p6 54-57/60
  18. xIshtar

    GUYS LAST EXAM....SADDEST DAY OF MY LIFE

    Doing Chemistry, Physics, Biology and A2 Maths :D
  19. xIshtar

    Chemistry paper 31- how was it? :D

    Pretty good :D
  20. xIshtar

    Chemistry paper 31 (NEW)

    I wrote photosynthesis and a cell :D
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