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AS Chemistry Question MCQ

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kratos009:
Hey guys
I got one Chemistry multi-choice question where i don't understand how they got the answer,

1.Aluminium chloride catalyses certain reactions by forming carbocations (carbonium ions) with
chloroalkanes as shown.
RCl + Al Cl3 ? R+ + AlCl4-


Which property makes this reaction possible?
A AlCl3 exists as the dimer Al2Cl6 in the vapour.
B AlCl3 is a covalent molecule.
C The aluminium atom in Al Cl3 has an incomplete octet of electrons.
D The chlorine atom in RCl has a vacant p orbital.


The answer was C. Could someone explain to me why the AlCl3 has an incomplete octet, because doesn't the aluminium ion give away its three electrons to the Cholride ions?

123:
Hey this is explained in that Chem MCQ helps book...i think its in pg. 18 (left bottom) : Q18
Heres that book if u don;t hav 1: http://www.megaupload.com/?d=7CBYEBYX

kratos009:
Thanks a lot 123,  i understand it now.
If you have Chem exam tomorrow, GOOD LUCK.

Oh i just got one more question,

1.How does ammonia behave when its aqueous solution is used to dissolve silver chloride, AgCl ?

A as a base
B as a ligand with the Ag+ ion
C as a ligand with the Cl– ion
D as a reducing agent

the answer was B. I was wondering how does ammonia bind with the positive Ag+ ion, i thought it would bind with the negatively charged chloride ion as an ammonium chloride?thanks

ghl23:
if i've not mistaken, when ammonia is added to silver chloride.. it reacts with silver to form a soluble complex Ag(NH3)2+ and also liberating Cl- ions

AgCl(s) + 2NH3(aq) ? Ag[(NH3)2]+(aq) + Cl?(aq)

top_dog77:
thanks for the upload

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