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  1. Pals_1010

    Chemistry Paper 2

    No, it isn't This formula is applicable only when we talk about ΔH of formation. Then it becomes, ΔH of reaction = ΔH of formation of products - ΔH of formation of reactants But, the date given in the question was ΔH of combustion. So. you have to construct a cycle and apply Hess' Law
  2. Pals_1010

    Chemistry Paper 2

    Applying Hess' Law, ΔH = (-283) + (2x-286) + -(-726) = -855 + 726 = - 129 kJmol-1
  3. Pals_1010

    GT for Chemistry paper 22 AS.

    Yup that's right :)
  4. Pals_1010

    GT for Chemistry paper 22 AS.

    When G is reduced?
  5. Pals_1010

    GT for Chemistry paper 22 AS.

    Yeah, they won't penalise you each time... E.c.f .... And besides you ended with a triol for the last part?
  6. Pals_1010

    Chem p22

    I know... I already multiplied it by two in the above post for number of moles of ATOMS
  7. Pals_1010

    Chem p22

    Nice saying :)
  8. Pals_1010

    Chem p22

    I got that as well... Let's hope for the best then...
  9. Pals_1010

    Chem p22

    You got which answer?
  10. Pals_1010

    Chem p22

    In fact, I think you had to multiply. You round off your figures only when the difference between the whole number is 0.1 (like 1.1 becomes 1 or 8.9 becomes 9) and it's very very close (7.9888888...) .... In this case, the values were too far to simply round off
  11. Pals_1010

    Chem p22

    Yeah, am pretty sure...
  12. Pals_1010

    Chem p22

    1) 6 marks 2) I would go with pH 2 as HCl is produced when SiCl4 reacts with water. 3) -129 kJmol-1 4) You found the no of moles of H atoms in the previous part right? That means 0.30 g of G releases 6.67 x 10^-3 mol of H atoms with Na 90 g (Mr of G) , which is also 1 mol of G, releases...
  13. Pals_1010

    GT for Chemistry paper 22 AS.

    Yes, it is in the syllabus: The reaction with steam catalysed by phosphoric acid to produce alcohols. Am not denying the fact that halogens react by this mechanism. In fact, both steam and halogens react with alkenes by electrophilic addition. That's what I am saying
  14. Pals_1010

    Chemistry paper 52 discussion

    Umm... the plotting graph question was around 4 marks according to the post above. 4 marks maybe
  15. Pals_1010

    Chemistry paper 52 discussion

    Actually yes. it was (1/V) against P.... You ll probably only lose marks for the plotting of graph though. Then e.c.f for the following parts (gradient etc) :)
  16. Pals_1010

    Chemistry paper 52 discussion

    It is a straight line initially, then it becomes curved.
  17. Pals_1010

    GT for Chemistry paper 22 AS.

    http://www.docbrown.info/page06/OrgMechs1b.htm#catalysed With steam also.... My job here is done
  18. Pals_1010

    Chemistry paper 52 discussion

    *fingers crossed* :D
  19. Pals_1010

    GT for Chemistry paper 22 AS.

    Halogenoalkanes undergo Nucleophilic Substitution
  20. Pals_1010

    Chemistry paper 52 discussion

    independent variable: mass of ammonium nitrate dependent variable : volume of N2O other control : temperature
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