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Chemistry: Post your doubts here!

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View attachment 58131
25 a and b
I guess I know the answer, but I am not sure if I am 100% correct.
a) From all three Cr2+ has least positive E(std) value. Hence it needs the strongest reducing agent (more -ve E(std) value agent) to reduce it.
b) From all three Ag has most posivtive E(std) value. Hence it needs the strongest oxidising agent (more +ve E(std) value agent) to oxidise it.
M I corrct? If not then do correct me. Thanks.
Metanoia
DarkEclipse
Dark Destination
awesomaholic101
FranticAmaze
My Name
Didn't get the tag. :eek:
I think you're answers are right.
Doesn't the book have answers at the back?
awesomaholic101 FranticAmaze Midnight dream Lola_sweet What do you say?
 
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View attachment 58131
25 a and b
I guess I know the answer, but I am not sure if I am 100% correct.
a) From all three Cr2+ has least positive E(std) value. Hence it needs the strongest reducing agent (more -ve E(std) value agent) to reduce it.
b) From all three Ag has most posivtive E(std) value. Hence it needs the strongest oxidising agent (more +ve E(std) value agent) to oxidise it.
M I corrct? If not then do correct me. Thanks.
Metanoia
DarkEclipse
Dark Destination
awesomaholic101
FranticAmaze
My Name

Yes. That is correct. You can also use O level chemistry to check your answer- in decreasing reactivity of metals, Chromium, Iron and Silver.

So the most stable ion is Cr2+ and the most stable metal is Ag.

They will require the strongest reducing agent and oxidizing agent respectively to under changes.
 
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Anyone with the new 2016 coursebook, please can you tell me if High-performance liquid chromatography (HPLC) is given in the text book??
It's not in the syllabus so do I need it??
 
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Yes. That is correct. You can also use O level chemistry to check your answer- in decreasing reactivity of metals, Chromium, Iron and Silver.

So the most stable ion is Cr2+ and the most stable metal is Ag.

They will require the strongest reducing agent and oxidizing agent respectively to under changes.
THanks.... :)
 
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When concentrated nitric acid, HNO3, is added to copper turnings, a brown gas is evolved. Use data from the Data Booklet to construct an ionic equation for this reaction.
which equation of copper should i use and why ?
 
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When concentrated nitric acid, HNO3, is added to copper turnings, a brown gas is evolved. Use data from the Data Booklet to construct an ionic equation for this reaction.
which equation of copper should i use and why ?
Well you should use this eq. :Cu + 4H+ + 2NO3– → Cu2+ + 2NO2 + 2H2O. Because it is ionic :3
 
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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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