Chem 5 jun 05 ms wrong? Watch

dodo123
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AQA syllabus

Deduce the role of copper metal in the formation of [CuCl4]3– from the
copper-containing species in solution D (which is [CuCl4]2-).
So oxidation state of Cu to begin with is +2 and goes to +1 in the 3- complex. Therefore it acts as an Oxidising agent because reduction is loss of oxidation number (i.e. goes down) doesn't it?

Mark scheme says its a reducing agent :confused:
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charco
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(Original post by dodo123)
AQA syllabus


So oxidation state of Cu to begin with is +2 and goes to +1 in the 3- complex. Therefore it acts as an Oxidising agent because reduction is loss of oxidation number (i.e. goes down) doesn't it?

Mark scheme says its a reducing agent :confused:
By the wording of the question it seems that there is a reaction between copper metal and the complex [CuCl4]2-
to form [CuCl4]3-

You are correct in your assessment of what happens to copper in the complex, it goes from II to I (it is reduced), therefore it is the copper metal that is reacting with the complex that is the reducing agent.
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counterstrike91
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Its from [CuCl4]2- to [CuCl4]3- thus the copper acts as a reducing agent as oxidation state of copper in complex goes from +2 to +1 (gains an electron) so the copper metal acts as reducing agent as it itself is oxidised
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dodo123
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err if it gains an electron isnt it reduced thus it is an oxidising agent ? :confused:
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counterstrike91
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asking about the copper metal that you add, not the original copper in the complex.
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quietpeople_x
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Does anyone know for sure the answer to this question because I am having the same problem and I would don't know who to ask?
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dip0
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(Original post by quietpeople_x)
Does anyone know for sure the answer to this question because I am having the same problem and I would don't know who to ask?
The MS is correct, I.e. is a reducing agent,
It's oxidation state goes from +1 to +2. It's lost electron so it's oxidised, but it's a reducing agent as the electron is accepted by another species, hence the Cu containing species has reduced the other species so reducing agent is the answer.
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quietpeople_x
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(Original post by dip0)
The MS is correct, I.e. is a reducing agent,
It's oxidation state goes from +1 to +2. It's lost electron so it's oxidised, but it's a reducing agent as the electron is accepted by another species, hence the Cu containing species has reduced the other species so reducing agent is the answer.
Here is the copy pasted question:


  1. The oxidation state of copper in [CuCl4]3– is +1.

    1. Deduce the role of copper metal in the formation of [CuCl4]3– from the
      copper-containing species in solution D.

      on the ms D is:

      1. identity: [CuCl4]2-;

        the ox state in D is +2 and the ox state in [CuCl4]3– +1

        since its saying the formation of [CuCl4]3– its going from +2-->+1 which is oxidation.

        that is where my head it at where am I going wrong?
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dip0
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(Original post by quietpeople_x)
Here is the copy pasted question:
quick defintions:

oxiding agent = species which oxidises something else (so the oxidising agent gains an electron because it lost an electron from the "something else" )
reducing agent = species which reduces something else (so the reducing agent loses an electron because it needs to lose an electron from itself to transfer it to the "something else" )

[CuCl4]2- is oxidised as as you said, this will fit in with reducing agent definition.
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quietpeople_x
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(Original post by dip0)
quick defintions:

oxiding agent = species which oxidises something else (so the oxidising agent gains an electron because it lost an electron from the "something else" )
reducing agent = species which reduces something else (so the reducing agent loses an electron because it needs to lose an electron from itself to transfer it to the "something else" )

[CuCl4]2- is oxidised as as you said, this will fit in with reducing agent definition.
Shoot! Oh my lord of course, that is a dumb thing to forget aha
Thank you!!
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