H2 Chemistry 2013 'A' Levels P2 & P3 & P1

• Ilovechem

  26 Nov 13, 23:17

  Hi isn't qn 4 B? The I.e given resembles Ti in data booklet and also TM have similar IE. Thus the element given is a TM!

• UltimaOnline

  26 Nov 13, 23:27

  Originally posted by Ilovechem:

  Hi isn't qn 4 B? The I.e given resembles Ti in data booklet and also TM have similar IE. Thus the element given is a TM!

  
  Transition metals have variable oxidation states, and thus could form multiple chlorides. The question specifies that this unknown element only forms one possible chloride.

• Blanklorh

  27 Nov 13, 09:35

  erm for qn 36, i worked out the elec config of In to be 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p1

  to my understanding, partially filled d orbital shld give colour no? then ionic salt of In(III) ought to be able to have a d-d transition isnt it? hence the colour? 

• UltimaOnline

  27 Nov 13, 09:45

  Originally posted by Blanklorh:

  erm for qn 36, i worked out the elec config of In to be 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p1

  to my understanding, partially filled d orbital shld give colour no? then ionic salt of In(III) ought to be able to have a d-d transition isnt it? hence the colour? 

  
  Good thoughtful effort, you did indeed successfully work out the electron configuration.

  But unfortunately, you're slightly off target when it comes to ionizing, as electrons are always removed from outer quantum shells first :

  In = [Ar] 4d10 5s2 5p1

  In+ = [Ar] 4d10 5s2 5p0

  In2+ = [Ar] 4d10 5s1 5p0

  In3+ = [Ar] 4d10 5s0 5p0

  Hence In3+ in it's ionic salts have a fully filled d subshell, hence no d-d* electron transitions, hence it's ionic salts are not coloured.

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  Posted by Prototype445

  Oh I only answered B because I assumed since chemical properties are the same
  Electronic config will have fully filled d orbitals like Al3+ so no colour
  I don't know if my thought pattern is okay

  It's not valid to assume all Group III elements have the same chemical properties. Not a valid shortcut.
  
  Rather, the correct valid shortcut to this question, is to recognize that Indium is a p block element, not a d block element, and so cannot have partially filled d orbitals in its compounds, which therefore cannot be coloured.
  

• Blanklorh

  27 Nov 13, 10:33

  oh no TT given this paper im wondering if my approx 31/40 is even a good enough grade. almost all are due to carelessness :/

• UltimaOnline

  27 Nov 13, 13:34

  Originally posted by Blanklorh:

  oh no TT given this paper im wondering if my approx 31/40 is even a good enough grade. almost all are due to carelessness :/

  
  31/40 = 77.5%.

  If you did similar or better for your other papers (including SPA), then your A grade is very secure.

  This year's A grade threshold on the bell-curve should be between 73-75%.

   

• Dunnolah95

  28 Nov 13, 20:41

  Thanks for the answers! May I ask, for question 34, why is the answer B instead of D? Isn't the anion O2-, so the number of electrons should be 10?

• UltimaOnline

  28 Nov 13, 23:54

  Originally posted by Dunnolah95:

  Thanks for the answers! May I ask, for question 34, why is the answer B instead of D? Isn't the anion O2-, so the number of electrons should be 10?

  
  The anion in this question, refers to the peroxide anion :