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Chemistry: Post your doubts here!

Metanoia

Metanoia

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_Ahmad said:
Can anyone PLEASE explain these question!



Q5,7,17,18,24,25,30,33,34 from
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w05_qp_1.pdf
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w05_ms_1.pdf
Click to expand...

Princess Raven said:
I could answer 5,6,25,30,33 if u figure out the rest plz tell me how to solve them as well!
Click to expand...

W05qp1

Q17. This question comes from the chapter of transition metals, I'm not sure its relevant to your syllabus now.

Q18. ammonium salt + base --> salt + water + NH3
ammonium sulfate + calcium hydroxide --> calcium sulfate + H2O + NH3
Nutrient of nitrogen in the fertilzer is lost as NH3 gas.

Q24. Three possible alkenes
cis -but-2-ene, trans-but-2-ene and but-1-ene
 
Metanoia

Metanoia

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Browny said:
Thanks so much for the help, I just coudn't figure out thee questions !!!(y)(y)(y)

But in 11 isn't the Cr oxidation number changed.
And in 12 there are others with the curve shifted and with a lower maximum like D for example.
And in 18 how can we know the structure of the compunds such as in D, beacause I think structure of that is not in our syllabus.
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Q11. The Cr is +6 before and after reaction.

Q12. Quite true, its was puzzling to me, the peak if shifted so far right would be really really low. So I prefer the other option. Its debatable.

Q18. That option is under transition metals, I believe is not required in your syllabus.
 
B

Browny

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Metanoia said:
Q11. The Cr is +6 before and after reaction.

Q12. Quite true, its was puzzling to me, the peak if shifted so far right would be really really low. So I prefer the other option. Its debatable.

Q18. That option is under transition metals, I believe is not required in your syllabus.
Click to expand...
In 12 can't C be a option as well?

And in 18 if it is not in our syllabus how can we answer that question without knowing the structure?

And going back to question 9, after calculating bond energies the bond energy required to break D is actually smaller so how to answer that question.

And in question 20 why can't B be correct.

And in question 30 can you please draw me the structure as I don't understand the compound. :)
 
Metanoia

Metanoia

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Browny said:
In 12 can't C be a option as well?

And in 18 if it is not in our syllabus how can we answer that question without knowing the structure?

And going back to question 9, after calculating bond energies the bond energy required to break D is actually smaller so how to answer that question.

And in question 20 why can't B be correct.

And in question 30 can you please draw me the structure as I don't understand the compound. :)
Click to expand...

Q12. Unfortunately, I feel its a poorly set question, as the scale is hard to compare. I feel peak of C is too high.

Q9. What I suggest is just a guide line, don't forget we need to factor in energy given out when H-O-H bonds are formed on the other side.

Q18. It is a paper that is set some years again, so its might be relevant then, but not this year.

Q30. Look for the ester bond on the right. Cut the C-O, and reform the CH3CH2OCH3 on the right, into an alcohol.
 
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Browny

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Metanoia said:
Q12. Unfortunately, I feel its a poorly set question, as the scale is hard to compare. I feel peak of C is too high.

Q9. What I suggest is just a guide line, don't forget we need to factor in energy given out when H-O-H bonds are formed on the other side.

Q18. It is a paper that is set some years again, so its might be relevant then, but not this year.

Q30. Look for the ester bond on the right. Cut the C-O, and reform the CH3CH2OCH3 on the right, into an alcohol.
Click to expand...
Metanoia sorry but I needed the structure of A in 30.

And in 9 in all the reactions H2O are formed, right?
 
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Browny

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$$AK$$ said:
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w13_qp_12.pdf

Doubts : Q5 - C , Q22 -C , Q24 -A , Q25 -B , Q29 -D

THNX :)

Metanoia Browny
Click to expand...
In 5 the rate should increase as the products which catalyse the reaction increase thereby elimination the answer D and also after some time as the reactants deacrease the reaction rate drops down as there are not enough reactants thereby answer being C.

In 22 the answer is C as K2Cr2O7 is not strong enough to oxidise the double bond but is strong enough to completely oxidise the alcohol to a carboxylic acid as it is hot and concentrated.

In 29 all of them will react and form the required salt as some are esters and some are carboxylic acids.

For question 25 do you know how to upload a paint file to show you how to work it.
 
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