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Chemistry: Post your doubts here!

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Hmm yeah ... But can't you multiply the Cu+ eqn by 2 so to get 2e-?
Copper is oxidized by concentrated nitric acid, HNO3, to produce Cu2+ ions; the nitric acid is reduced to nitrogen dioxide, a poisonous brown gas with an irritating odor. The question says brown gas is formed :p so here i win.
 
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Copper is oxidized by concentrated nitric acid, HNO3, to produce Cu2+ ions; the nitric acid is reduced to nitrogen dioxide, a poisonous brown gas with an irritating odor. The question says brown gas is formed :p so here i win.
What I'm saying is why can't it be this equation too:
NO3- + 2H+ + Cu = NO2 + H2O + Cu+
Here NO2 is also formed...

So can't it be either or equations?
---> 2NO3- + 4H+ + Cu = 2NO2 + 2H2O + Cu2+
---> NO3- + 2H+ + Cu = NO2 + H2O + Cu+
 
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Copper is oxidized by concentrated nitric acid, HNO3, to produce Cu2+ ions; the nitric acid is reduced to nitrogen dioxide, a poisonous brown gas with an irritating odor. The question says brown gas is formed :p so here i win.
What I'm saying is why can't it be this equation too:
NO3- + 2H+ + Cu = NO2 + H2O + Cu+
Here NO2 is also formed...

So can't it be either or equations?
---> 2NO3- + 4H+ + Cu = 2NO2 + 2H2O + Cu2+
---> NO3- + 2H+ + Cu = NO2 + H2O + Cu+
why can't we use Cu+ instead of Cu2+ ?
I think I got it
We can't use Cu+ because the voltage would give 0.29 and for a reaction to take place it should be greater than 0.30V
so Cu2+ should be used I guess...
 
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in 2002 october november
An aqueous solution of iron(III) chloride is used to dissolve the excess of copper metal from printed-circuit boards
the mark scheme allowed both Cu2+ and Cu+ despite the voltage being less than 0.3 V ,when using Cu+ .
 
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the idea of a reaction occurring if it's more than 0.3 V is if is under non-standard conditions. However, this was not mentioned in the question for nitric acid and copper
 
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in 2002 october november
An aqueous solution of iron(III) chloride is used to dissolve the excess of copper metal from printed-circuit boards
the mark scheme allowed both Cu2+ and Cu+ despite the voltage being less than 0.3 V ,when using Cu+ .
Is this A2 stuff lol :p ? :3 I'm an A's student
 
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in 2002 october november
An aqueous solution of iron(III) chloride is used to dissolve the excess of copper metal from printed-circuit boards
the mark scheme allowed both Cu2+ and Cu+ despite the voltage being less than 0.3 V ,when using Cu+ .
Hmmm... Winter 13 they haven't allowed Cu+
 
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the idea of a reaction occurring if it's more than 0.3 V is if is under non-standard conditions. However, this was not mentioned in the question for nitric acid and copper
upload_2016-1-1_19-55-22.png
This is the examiner report... they don't mention why Cu+ is technically incorrect though...
 
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How to do question 2.a.ii
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s13_qp_41.pdf
Summer 13 P41
Is there any formula which says how to do it??
The ms is confusing and I can't see anything in text book :/
Metanoia
Someone please help!

To show that the reaction is first order with respect to the reactant in the y-axis. Draw lines to figure out the half-lives (duration for a concentration to drop to half its value).

The convenient ones I've chosen for this question is the time taken to drop from 0.2 M to o.1M, and time taken to drop from 0.1 M to 0.05 M.

For 1st order, the durationsScreen Shot 2016-01-02 at 8.52.50 AM.jpg should be the same.
 
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