hard transition metal question

Watch this thread
usernamenew
Badges: 9
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#1
Report Thread starter 3 years ago
#1
When cobalt (II) chloride is treated, under certain conditions, with the bidentate ligand, NH2CH2CH2NH2, (which can be represented by the symbol “en”), the compound [CoC12(en)2]Cl is formed.
(i) What is the oxidation state of cobalt in the compound formed? What is the co-ordination number of cobalt in this compound?
the markscheme says ox s is 3 and coordination number is 6, how do they get that? isn't cobalt +2?
0
reply
usernamenew
Badges: 9
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#2
Report Thread starter 3 years ago
#2
(Original post by usernamenew)
When cobalt (II) chloride is treated, under certain conditions, with the bidentate ligand, NH2CH2CH2NH2, (which can be represented by the symbol “en”), the compound [CoC12(en)2]Cl is formed.
(i) What is the oxidation state of cobalt in the compound formed? What is the co-ordination number of cobalt in this compound?
the markscheme says ox s is 3 and coordination number is 6, how do they get that? isn't cobalt +2?
When hydrazine, NH2NH2, reacts with cobalt (II) chloride in aqueous solution, the compound CoCl2(NH2NH2)2 is formed. This compound has a polymeric structure in which cobalt is six co-ordinate and the cobalt ions are linked by hydrazine molecules. Draw the structure of the repeating unit of the polymer.

Deduce the structural formula of the complex compound CoCl3.4NH3, in which cobalt has the same oxidation state and co-ordination number as in [Co(NH3)6]Cl3
Last edited by usernamenew; 3 years ago
0
reply
j.hdxr
Badges: 9
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#3
Report 3 years ago
#3
that is one tough nut to crack. the markscheme doesn't help as well. hopefully, someone can answer this.
0
reply
username3249896
Badges: 12
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#4
Report 3 years ago
#4
[CoCl2(en)2]Cl
charge on Cl- ligands = -1
charge on en ligands = 0
charge on Cl- ion = -1
let charge on Co be x
x + 2(-1) + 2(0) -1 = 0
x = +3

Coordination number is 6

NH2NH2 has 1 lone pair on each N atom. One of the lone pairs is used to datively bond to the Co ion and the other one is used to bridge the ion to the next one, forming a polymeric structure. Draw the repeat unit

in [Co(NH3)6]Cl3
oxidation state is +3 and co-ordination number is 6

the compound is [Co(NH3)4Cl2]Cl
The NH3 must be bound to the central metal ion because they are uncharged and cannot balance out any charge remaining on the ion
One Cl- ion balances the charge of the [Co(NH3)4Cl2]+ ion

(Original post by usernamenew)
When hydrazine, NH2NH2, reacts with cobalt (II) chloride in aqueous solution, the compound CoCl2(NH2NH2)2 is formed. This compound has a polymeric structure in which cobalt is six co-ordinate and the cobalt ions are linked by hydrazine molecules. Draw the structure of the repeating unit of the polymer.

Deduce the structural formula of the complex compound CoCl3.4NH3, in which cobalt has the same oxidation state and co-ordination number as in [Co(NH3)6]Cl3
0
reply
j.hdxr
Badges: 9
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#5
Report 3 years ago
#5
Oh shoot, i didn't realise the oxidation state was +3.
Thanks for your help and Good luck on your revision
(Original post by BobbJo)
[CoCl2(en)2]Cl
charge on Cl- ligands = -1
charge on en ligands = 0
charge on Cl- ion = -1
let charge on Co be x
x + 2(-1) + 2(0) -1 = 0
x = +3

Coordination number is 6

NH2NH2 has 1 lone pair on each N atom. One of the lone pairs is used to datively bond to the Co ion and the other one is used to bridge the ion to the next one, forming a polymeric structure. Draw the repeat unit

in [Co(NH3)6]Cl3
oxidation state is +3 and co-ordination number is 6

the compound is [Co(NH3)4Cl2]Cl
The NH3 must be bound to the central metal ion because they are uncharged and cannot balance out any charge remaining on the ion
One Cl- ion balances the charge of the [Co(NH3)4Cl2]+ ion
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Back
to top
Latest

How did The Student Room help you with your university application?

Talking to current university students (19)
18.63%
Talking to peers going through the same thing (35)
34.31%
Speaking to student ambassadors from the universities (6)
5.88%
Speaking to staff members from universities (2)
1.96%
Using the personal statement builder, library or helper service (10)
9.8%
Reading articles about what steps to take (19)
18.63%
Learning about/speaking to Student Finance England (4)
3.92%
Something else (tell us in the thread) (7)
6.86%

Watched Threads

View All