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  1. Metanoia

    Chemistry: Post your doubts here!

    heat of reaction x moles of water formed = mass of solution heated x temperature change x specific heat capacity of solution Are you able to figure out the values to use for the following? moles of water formed = mass of solution heated = temperature change = specific heat capacity of solution =
  2. Metanoia

    Chemistry: Post your doubts here!

  3. Metanoia

    Chemistry: Post your doubts here!

    Nucleophiles contain lone pairs, but are not necessary negatively charged. Examples of commonly encountered neutral nucleophiles are H2O and NH3.
  4. Metanoia

    Chemistry: Post your doubts here!

    Convert the masses of ethanol and ethanoic acid to moles to figure out the limiting reagent. Limiting reactant is acid, 0.5 moles. Expected moles of ester is thus 0.5 moles, 44g. %yield = 22/44 = 50%
  5. Metanoia

    Solutions to Challenging 9701 MCQ Paper 1

    Thank you, much appreciated. The resources are available for purchase for those who are interested. Otherwise, students are also free to post their doubts in the official threads for help.
  6. Metanoia

    Chemistry: Post your doubts here!

    Compared to the others, CO2 has the strongest intermolecular forces of attraction. An ideal gas is supposed to have negligible intermolecular forces of attraction.
  7. Metanoia

    Chemistry: Post your doubts here!

    Your bottom two isomers are identical. Instead, find the chiral carbon in the 2nd isomer (top row), indicating that there is an extra optical isomer. The question has hinted to look for optical isomers, so likely there will be at least one.
  8. Metanoia

    Chemistry: Post your doubts here!

    Q1. Form a balance equation for the reaction. Pb4+ + 2Br- --> Pb2+ + Br2 Moles of Pb4+ = 6.980/Mr of PbCl4 Work towards moles of Br2..... Q7. 2 moles of NF3 are broken down into its atoms, so 6 moles of N-F bonds are broken. Each N-F requires = + 1668/6 kJ of energy (positive as it is...
  9. Metanoia

    Chemistry: Post your doubts here!

    It is not necessary to find the number of moles (which are the same in the beginning and the end).
  10. Metanoia

    Chemistry: Post your doubts here!

    That is correct, rate is dependent on temp, concentration and presence of catalyst. Equilibrium is a ratio of the forward rate and backward rate. In option D, the forward rate remains the same while the backward rate decreases.
  11. Metanoia

    Chemistry: Post your doubts here!

    Imagine the molecule flat on a table. Visualise placing your fingers where the Cl atoms are and apply a pulling force. You should be able to see that molecule B "moves upwards" (due to an overall dipole moment) , whereas molecule D remains stationary. Its analogous to forces in physics.
  12. Metanoia

    Chemistry: Post your doubts here!

    The Cl atoms are electronegative, look for the symmetry, D has the Cl pulling the electrons in opposite directions and canceling each other out.
  13. Metanoia

    Chemistry: Post your doubts here!

    Create a balance equation on the combustion. Figure out which is the limiting reactant and what gases of CO2 and O2 you have left over.
  14. Metanoia

    Chemistry: Post your doubts here!

    Yes. NaAlOH4 is a salt. I'm surprised it can react with cold NaOH. But having reread the question and having to choose between Al2O3 and SiO2, I guess SiO2 is more unreactive due to its giant covalent structure.
  15. Metanoia

    Chemistry: Post your doubts here!

    Hmm..I reread the question, now I understand your confusion. Seems to me both A and D are possible answers. This is a past year question?
  16. Metanoia

    Chemistry: Post your doubts here!

    It's an ester, check the naming rules for ester. Hot conc NaOH is needed for reaction. Do not forget that Al2O3 is a protective inert layer.
  17. Metanoia

    Chemistry: Post your doubts here!

    There are 2 C=C bonds. Cis cis Cis trans Trans trans
  18. Metanoia

    Chemistry: Post your doubts here!

    Draw the isomers that you have, likely you have 2 of the same kinds.
  19. Metanoia

    Chemistry: Post your doubts here!

    If the solid reactant is not soluble in water itself, it would be observed to "dissolve" when it can react with acid to form a soluble salt. Solid reactants "dissolving " with acids commonly follow these reactions Base (s) + acid Carbonate (s) + acid Metal (s) + acid BaSO4 belongs to none of them.
  20. Metanoia

    Chemistry: Post your doubts here!

    volume needs to be converted to m3.
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