Chemistry: Post your doubts here!

[♣♠ Magnanimous ♣♠]

Thank you!

No probs

 

[♣♠ Magnanimous ♣♠]

How did u convert grams to moles?

Umm,

Mass = Moles * Mass of 1 mole (Molar Mass)
So moles = mass / mass of 1 mole right?
now put values simple

 

[♣♠ Magnanimous ♣♠]

conc in g per dm^3 = conc in mol * Mr
so conc in mol= conc in g per dm^3 / Mr

Thoda achi tarah se samjao
Muje bhi samaj nahi aya usko kya ayega :/

 

[Pink Flower]

Umm,

Mass = Moles * Mass of 1 mole (Molar Mass)
So moles = mass / mass of 1 mole right?
now put values simple

Ohh Thanks!
I did not have a good teacher in my AS....and she did not even touch upon the chapter of moles saying that its easy..and just read from the book...I got a C in my May/June session and I am,pretty much self studying, repeating to get a better grade... Thanks for the help.

Thoda achi tarah se samjao
Muje bhi samaj nahi aya usko kya ayega :/

And there are some days that a mind is blank..........

 

[♣♠ Magnanimous ♣♠]

Ohh Thanks!
I did not have a good teacher in my AS....and she did not even touch upon the chapter of moles saying that its easy..and just read from the book...I got a C in my May/June session and I am,pretty much self studying, repeating to get a better grade... Thanks for the help.

And there are some days that a mind is blank..........

You have teaceers, I didn't have teacher of chem
I did everything myself

 

[Charlotte20102013]

Q3.
Ti+ --> Ti3+ + 2e-

moles of Ti+ : moles of e- : moles of VO3-
0.003 moles : ? : 0.002 moles
3 moles : ? moles : 2 moles

Using the half equation, we can see that 3 moles of Ti+ will transfer 6 moles of electrons to 2 moles of VO3-.

In other words, 1 mole of VO3- gains 3 moles of electrons (its oxidation number would decrease by 3 units).

Original oxidation number of vanadium in VO3- is +5, final oxidation number would then be +2 (since it decreases by 3 units).

Q15.
NH3 is a stronger base than H2O, so we have NH3 accepting protons from H2O

NH3 + H2O <--> NH4+ + OH-

Q23.
Using cold dilute KMnO4, we will add OH to each of the carbons across the C=C double bonds.

Q27.
It should be a tertiary alcohol as it is not oxidized. The carbon holding the OH is expected to be joined to 3 other branches containing different number of carbons.

......C
C2-C-C3
.....OH

Q38. Which option are you unsure of? See if you can google for the mechanism of the reaction.

Q39.
Option 1 is correct
CH3CH2CH2OH (alcohol) can be oxidized to CH3CH2CO2H (acid)
CH3CH2CH2OH (alcohol) and CH3CH2CO2H (acid) can undergo esterifcation to form the desired product.

Option 2 is correct
CH3CH2CHO (aldehyde) can be oxidized to CH3CH2CO2H (acid)
CH3CH2CHO (aldehyde) can be reduced to CH3CH2CH2OH (alcohol)
CH3CH2CH2OH (alcohol) and CH3CH2CO2H (acid) can undergo esterifcation to form the desired product.

Thank you very much! And I can see that you've prepared videos on the past MCQ questions for us A level students too. Thanks for that also, I'm sure it will help a whole lot of students !

 

[RoOkaYya G]

Thoda achi tarah se samjao
Muje bhi samaj nahi aya usko kya ayega :/

achaw?

 

[f.mohamed]

Does anyone know where can i find a classified past paper for unit 1 ?
Thanks in advance

 

[♣♠ Magnanimous ♣♠]

achaw?

Sahi to bola

 

[♣♠ Magnanimous ♣♠]

Does anyone know where can i find a classified past paper for unit 1 ?
Thanks in advance

Classified papers means

 

[f.mohamed]

Classified papers means

I mean topic wise

 

[♣♠ Magnanimous ♣♠]

I mean topic wise

Oh yeah! There is a thread which contains topical answers( topic wise) Will give you link after some hours! In hurry to school right now

 

[♣♠ Magnanimous ♣♠]

I mean topic wise

https://www.xtremepapers.com/community/threads/as-chemistry-topical-finally-here.23520/

 

[f.mohamed]

https://www.xtremepapers.com/community/threads/as-chemistry-topical-finally-here.23520/

Thankk youuu !!

 

[♣♠ Magnanimous ♣♠]

No probs

Thankk youuu !!

 

[Abdel Moniem]

I Scored a U in chemistry AS practicals although my components for paper 1 and 2 were an A and a B. I practiced Paper 3 a lot and yet me and all of my friends scored the same grade. Can anyone give me some tips to follow to score an A grade or a B grade for my paper 3

 

[♣♠ Magnanimous ♣♠]

I Scored a U in chemistry AS practicals although my components for paper 1 and 2 were an A and a B. I practiced Paper 3 a lot and yet me and all of my friends scored the same grade. Can anyone give me some tips to follow to score an A grade or a B grade for my paper 3

https://www.xtremepapers.com/commun...ok-free-download-post-your-doubts-here.33074/

 

[Abdel Moniem]

https://www.xtremepapers.com/commun...ok-free-download-post-your-doubts-here.33074/

Thank you so much

 

[♣♠ Magnanimous ♣♠]

Thank you so much

No probs

 

[savera]

hi ,
for an example
http://www.cie.org.uk/images/157296-november-2012-question-paper-43.pdf
question number 7 iii

I can solve the 7 i and ii
and from the question i know there will have 2 -CH3 group and 2-CH2 group
and one of the element beside C and H is O

and according to chemical shift ,
there is some group in ~around 1 and 2.5
but everytime i cant find something fit to information

here is the data booklet :
http://fmcapechemistry.weebly.com/uploads/5/6/3/3/5633072/chem_data_booklet.pdf

Sorry but I hav

hi ,
for an example
http://www.cie.org.uk/images/157296-november-2012-question-paper-43.pdf
question number 7 iii

I can solve the 7 i and ii
and from the question i know there will have 2 -CH3 group and 2-CH2 group
and one of the element beside C and H is O

and according to chemical shift ,
there is some group in ~around 1 and 2.5
but everytime i cant find something fit to information

here is the data booklet :
http://fmcapechemistry.weebly.com/uploads/5/6/3/3/5633072/chem_data_booklet.pdf

Sorry I cant help you, because I havnt done the applications part. I thought you were talking about the electrolysis part. So sorry I couldnt help you.Hope you find what your looking for.
btw have you complete the A2 syllabus.