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Chemistry: Post your doubts here!

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Browny

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Can anybody tell me whether all the workings are needed in the calculations(especially titrations) in paper 3?
In marking schemes they put all steps into 1 working step.
 
B

Browny

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Mohammed salik said:
View attachment 40711

look at Highlighted Parts!!
Click to expand...
Problem is should we show the workings step by step because in some papers there are questions to calculate the moles and then the concentration in same part.
If we want we can simplify and write it down in one step like the marking scheme does. But what should we do actually simplify or write it step wise?

And another question is H2O2 a oxidising agent or a reducing agent and why?

One more, is silver sulfate a prercipitate? Because when doing a paper i thought that if their is a sulfate ion if we test that for Cl-(although it doesn't have) we might get a white precipitate if silver sulfate is ppt. and that might mislead us to thinking it has a Cl- ion.
 
robinhoodmustafa

robinhoodmustafa

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First tell me that can I right Co2 instead of Carboxylic Acid when Alkene undergoes reaction with KMNO4 hot concentrated. because like the end product of hot Kmno4 is always co2 gas


Secondly.. how B and C are chiral ? (written in Ms) like they dont have different functional group attached to it.
IMG_20140501_154959.jpg
9701 paper 23 May june 2012.

Suchal Riaz
 
M

Mohammed salik

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Browny said:
Problem is should we show the workings step by step because in some papers there are questions to calculate the moles and then the concentration in same part.
If we want we can simplify and write it down in one step like the marking scheme does. But what should we do actually simplify or write it step wise?

And another question is H2O2 a oxidising agent or a reducing agent and why?

One more, is silver sulfate a prercipitate? Because when doing a paper i thought that if their is a sulfate ion if we test that for Cl-(although it doesn't have) we might get a white precipitate if silver sulfate is ppt. and that might mislead us to thinking it has a Cl- ion.
Click to expand...
Its Better If you Show Ur working and Be on Safe Side :)..

And H2O2 is Oxidizing Agent because H2O2 itself is reduced... while reacting it loses Oxygen to form water which is reduction.
eg . 2H+(aq) + H2O2(aq)+2Fe2+(aq) -> 2Fe3+(aq) +2H2O(l)

And yes Silver sulphate is insoluble . but i dont get your question?! :)
 
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M

Mohammed salik

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robinhoodmustafa said:
First tell me that can I right Co2 instead of Carboxylic Acid when Alkene undergoes reaction with KMNO4 hot concentrated. because like the end product of hot Kmno4 is always co2 gas


Secondly.. how B and C are chiral ? (written in Ms) like they dont have different functional group attached to it.
View attachment 40722
9701 paper 23 May june 2012.
Suchal Riaz
Click to expand...
But if You read the question carefully it says Write the Formula of ORGANIC Product.. so CO2 is Not ORGANIC :p

Plz look at attachments.. (I m Sorry For Bad Drawing ) :)

Chem.JPG
 
B

Browny

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Mohammed salik said:
Its Better If you Show Ur working and Be on Safe Side :)..

And H2O2 is Oxidizing Agent because H2O2 itself is reduced... while reacting it loses Oxygen to form water which is reduction.
eg . 2H+(aq) + H2O2(aq)+2Fe2+(aq) -> 2Fe3+(aq) +2H2O(l)

And yes Silver sulphate is insoluble . but i dont get your question?! :)
Click to expand...
Thanks.

So basically your are saying to write all the working step by step without joining them into one step huh?

OK, the other question is say there is a a salt having both a Cl- and a sulfate ion, how do we confirm it has a Cl- ion?
Because if we test with AgNO3 we will anyway get a precipitate with both the 2 anions.
 
M

Mohammed salik

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robinhoodmustafa said:
Mohammed salik
Click to expand...
Browny said:
Thanks.

So basically your are saying to write all the working step by step without joining them into one step huh?

OK, the other question is say there is a a salt having both a Cl- and a sulfate ion, how do we confirm it has a Cl- ion?
Because if we test with AgNO3 we will anyway get a precipitate with both the 2 anions.
Click to expand...
Much Better Question this Time...
You could Use Silver then Do conformatory test with Ammonia.. only Chloride Is Soluble..
Or You could use Barium Compound.. which gives Ppt with Sulphate Ion only :)!
 
M

Marwaa

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can someone explain to me the difference between calculating the amount ,in moles, of hydrogen atoms and hydrogen molecules?
 
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