• We need your support!

    We are currently struggling to cover the operational costs of Xtremepapers, as a result we might have to shut this website down. Please donate if we have helped you and help make a difference in other students' lives!
    Click here to Donate Now (View Announcement)

Chemistry paper 4

Messages
355
Reaction score
95
Points
38
what about the most topic we have to study A LEVEL

ANY ONE HAS AN IDEA
 
Last edited:
Messages
70
Reaction score
39
Points
18
I would really appreciate if someone would help me with the configuration of chromium 3+ and manganese 2+ why are the electrons removed from the 4s orbital rather than 3d. Please help.
 
Messages
1,035
Reaction score
539
Points
123
can someone explain these observations ?
as you can see the second compound contains double bonds in the benzene ring while the first compound doesn't. Now you should know this that when Br2 is added to any alkene(double bond) it is decolourised. You should know this if you've done As level organic :p

when NaNO2/HNO2 + HCl under 5degrees is added to the second compund it forms Benzene diazonium chloride(BDC)Benzenediazonium-chloride-2D-skeletal.png . this process is called diazotisation. This is followed by the addition of Phenol under alkaline medium to give Azodyedye3.gif 250px-Typical_azo_compound.svg.png which is the yellow precipitate in the observation :p

I know this all sounds insane at first but organic is basically Ratta. Just start from 2002 onwards and solve only the organic questions of every paper, you'll get the hang of it i'm sure :)
 
Last edited:
Messages
1,035
Reaction score
539
Points
123
I would really appreciate if someone would help me with the configuration of chromium 3+ and manganese 2+ why are the electrons removed from the 4s orbital rather than 3d. Please help.
alright, see, the maximum electrons d shells and an s shells can hold are 10 and 2 respectively. If d shell contains 5 electrons which is half of the total number of electrons(10) it can hold then it is said to be stable.
So for chromium the electronic configuration is 3d5 4s1, since 3d contains 5 electrons so is more stable than 4s which is also stable but becuase 4s electrons even further from the nucleus, therefore, the 4s electrons are pushed to a higher energy level than 3d.
Same is the case for Manganese.
 
Top