Chemistry: Post your doubts here!

[nehaoscar]

http://maxpapers.com/syllabus-mater...hment/9701_may-june-2011-all-question-papers/

Variant 22 - Question 1 - c - i
In part b iv
The moles of NaOH that reacted with acid are found to be 0.04 moles
So in part c i
Shouldn't the moles at equilibrium be 0.06 moles for the acid and ROH and 0.04 mol for ester and H2O (Since 0.04 reacts and originally 0.1 is present so left over = 0.1-0.04 = 0.06)
The mark scheme says other way round... how?

 

[Turki AbdulAziz]

For the substitution of alchohols to form halogenoalkanes, Sulphur dichloride oxide (SOCl2) can be used as a reagent. But the problem is what are the conditions for the reaction?? I've tried searching the internet but i got nothing. Can someone please help.

 

[princess Anu]

n

For the substitution of alchohols to form halogenoalkanes, Sulphur dichloride oxide (SOCl2) can be used as a reagent. But the problem is what are the conditions for the reaction?? I've tried searching the internet but i got nothing. Can someone please help.

no conditions..

 

[princess Anu]

why is the observation sol turns yellow and not that yellow green gas ie chlorine disappears?

 

[nehaoscar]

n

no conditions..

For the substitution of alchohols to form halogenoalkanes, Sulphur dichloride oxide (SOCl2) can be used as a reagent. But the problem is what are the conditions for the reaction?? I've tried searching the internet but i got nothing. Can someone please help.

Reflux

 

[asadalam]

why is the observation sol turns yellow and not that yellow green gas ie chlorine disappears?

What year is this?Shouldnt it be that the iodine is displaced from by Cl2,and that would give a brown color to the solution?Maybe if all the I is displaced that would lead to Cl2 going in excess and causing solution to turn yellow maybe?Still what year is this from?

 

[NIM]

View attachment 53071

Thank you soooo much!!

 

[Studydayandnight]

Can anyone show me to how to solve this??

 

[NIM]

Need help !!
9701/43/O/N/13
Q#5b

 

[The Sarcastic Retard]

Guys in the paper will we have to explain sp sp2 and sp3 hybridization?

You should have a rough idea. Its very useful for knowing shape and bond angles.

 

[Mahnoorfatima]

http://studyguide.pk/Past Papers/CIE/International A And AS Level/9701 - Chemistry/9701_w05_qp_2.pdf
In question 5 part f, shouldn't the aldehyde change into OO-C-R as the reaction of Tollen's reagent woth aldehyde yeilds:
CH3CHO+(Ag(NH3)2)+----> CH3COO- ?? Anyone?

 

[The Sarcastic Retard]

http://maxpapers.com/syllabus-mater...hment/9701_may-june-2011-all-question-papers/

Variant 22 - Question 1 - c - i
In part b iv
The moles of NaOH that reacted with acid are found to be 0.04 moles
So in part c i
Shouldn't the moles at equilibrium be 0.06 moles for the acid and ROH and 0.04 mol for ester and H2O (Since 0.04 reacts and originally 0.1 is present so left over = 0.1-0.04 = 0.06)
The mark scheme says other way round... how?

Moles of NaOH used is 0.045
Moles of NaOH that reacted with HCl is 0.005
Remaining NaOH that will react wid acid = 0.045-0.005 = 0.04
Hence 0.04 0.04 0.06 0.06

 

[nehaoscar]

Moles of NaOH used is 0.045
Moles of NaOH that reacted with HCl is 0.005
Remaining NaOH that will react wid acid = 0.045-0.005 = 0.04
Hence 0.04 0.04 0.06 0.06

But then 0.04 is the amount of acid with which the NaOH reacted
So would the equilibrium remaining mixture be 0.1 - 0.04 = 0.06 ?
Like I know it's not but please could you explain why

 

[nehaoscar]

But then 0.04 is the amount of acid with which the NaOH reacted
So would the equilibrium remaining mixture be 0.1 - 0.04 = 0.06 ?
Like I know it's not but please could you explain why

Moles of NaOH used is 0.045
Moles of NaOH that reacted with HCl is 0.005
Remaining NaOH that will react wid acid = 0.045-0.005 = 0.04
Hence 0.04 0.04 0.06 0.06

Oh wait nevermind! i just got it after reading the question! Thanks!

 

[asadalam]

Can anyone show me to how to solve this??

c part?

http://studyguide.pk/Past Papers/CIE/International A And AS Level/9701 - Chemistry/9701_w05_qp_2.pdf
In question 5 part f, shouldn't the aldehyde change into OO-C-R as the reaction of Tollen's reagent woth aldehyde yeilds:
CH3CHO+(Ag(NH3)2)+----> CH3COO- ?? Anyone?

Either is correct in recent paper as i saw in a question both were accepted RCOOH and RCOO- as the product of reaction with tollens.This is an old one so dont worry.

 

[nehaoscar]

Anyone have any last minute notes, tips and predictions for questions/topics that may come up tomorrow?

 

[Mahnoorfatima]

http://studyguide.pk/Past Papers/CIE/International A And AS Level/9701 - Chemistry/9701_w08_qp_2.pdf
How do I draw the hess cycle in Question 2 part cii?

 

[The Sarcastic Retard]

Anyone have any last minute notes, tips and predictions for questions/topics that may come up tomorrow?

Haha.. Just stay relaxed, dont be in hurry, but make sure you finish your paper in time.
Prediction : Everything is coming.

 

[The Sarcastic Retard]

http://studyguide.pk/Past Papers/CIE/International A And AS Level/9701 - Chemistry/9701_w08_qp_2.pdf
How do I draw the hess cycle in Question 2 part cii?

Like this :¬

 

[nehaoscar]

Haha.. Just stay relaxed, dont be in hurry, but make sure you finish your paper in time.
Prediction : Everything is coming.

Haha Chemical periodicity is my worst nightmare! (So is all of chem tbh )
And Maths P1 tomorrow too... ughh
Thanks though!