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[ CrCl 2 ( H 2 O ) 4 ] Cl ( H 2 O ) 2 [ CrCl 2 ( H 2 O ) 4 ] + + Cl + water size 12{ \[ ital "CrCl" rSub { size 8{2} } \( H rSub { size 8{2} } O \) rSub { size 8{4} } \] ital "Cl" cdot \( H rSub { size 8{2} } O \) rSub { size 8{2} } rightarrow \[ ital "CrCl" rSub { size 8{2} } \( H rSub { size 8{2} } O \) rSub { size 8{4} } \]rSup { size 8{+{}} } + ital "Cl" rSup { size 8{ - {}} } + ital "water"} {}

The light green compound with two reactive chlorines is apparently [ CrCl ( H 2 O ) 5 ] Cl 2 H 2 O size 12{ \[ ital "CrCl" \( H rSub { size 8{2} } O \) rSub { size 8{5} } \] ital "Cl" rSub { size 8{2} } cdot H rSub { size 8{2} } O} {} , while the violet compound with three reactive chlorines is Cr ( H 2 O ) 6 Cl 3 size 12{ ital "Cr" \( H rSub { size 8{2} } O \) rSub { size 8{6} } ital "Cl" rSub { size 8{3} } } {} .

Closely related to hydrate isomerism is ionization isomerism, where an ion takes the place of water. Consider two different compounds with the formula Co ( NH 3 ) 5 SO 4 Br size 12{ ital "Co" \( ital "NH" rSub { size 8{3} } \) rSub { size 8{5} } ital "SO" rSub { size 8{4} } ital "Br"} {} . One of these, [ Co ( NH 3 ) 5 ( SO 4 ) ] Br size 12{ \[ ital "Co" \( ital "NH" rSub { size 8{3} } \) rSub { size 8{5} } \( ital "SO" rSub { size 8{4} } \) \] ital "Br"} {} , appears red, whereas the other, [ Co ( NH 3 ) 5 Br ] SO 4 size 12{ \[ ital "Co" \( ital "NH" rSub { size 8{3} } \) rSub { size 8{5} } ital "Br" \] ital "SO" rSub { size 8{4} } } {} , appears violet.

In addition to these coordination sphere isomers there are geometrical isomers, which have coordination spheres of the same composition but different geometrical arrangement. Geometrical isomers are distinct compounds and can have different physical properties (although often not too different) such as color, crystal structure, melting point, and so on. For example, dichlorodiamine platinum (II) occurs in the square planar geometry (B) so the chlorine ligands can be either next to one another (cis) or opposite from one another (trans). The compound you will synthesize has an octahedral geometry with two (bidentate) "en" ligands, and two nitro ( NO 2 ) size 12{ \( ital "NO" rSub { size 8{2} } \) } {} ligands. The geometrical isomer you will make is the trans form, in which the NO 2 size 12{ ital "NO" rSub { size 8{2} } } {} ligands are not adjacent to one another. This difference between cis and trans octahedral isomers is shown in Fig 2.

Fig 2. The trans and cis geometrical isomers for octahedral complexes with two bidentate (“en”) and monodentate ( NO 2 ) size 12{ \( ital "NO" rSub { size 8{2} } \) } {} ligands specifically dinitrobis(ethylenediamine)Co(III). The two black balls represent the NO 2 size 12{ ital "NO" rSub { size 8{2} } } {} ligands and the two pairs of linked white balls represent the two ethylenediamine ligands. Cis and trans describe the relationship (relative position) between the two NO 2 size 12{ ital "NO" rSub { size 8{2} } } {} ligands. 

In the procedure that follows we start with a cobalt solution made from the salt hexaquacobalt(II) nitrate, [ Co ( H 2 O ) 6 ] ( NO 3 ) 2 size 12{ \[ ital "Co" \( H rSub { size 8{2} } O \) rSub { size 8{6} } \] \( ital "NO" rSub { size 8{3} } \) rSub { size 8{2} } } {} . When this salt dissolves it ionizes to form two ions of NO 3 size 12{ ital "NO" rSub { size 8{3} } rSup { size 8{ - {}} } } {} and one of Co ( H 2 O ) 6 2 + size 12{ ital "Co" \( H rSub { size 8{2} } O \) rSub { size 8{6} } rSup { size 8{2+{}} } } {} . We wish to prepare a Co(III) compound of ethylenediamine, so we must add ethylenediamine (en) and oxidize the Co(II) to Co(III). Because Co(II) is more reactive than Co(III), we allow it to react with (en) first, and then oxidize the resulting complex ion. In aqueous solution (en) reacts with water to produce OH size 12{ ital "OH" rSup { size 8{ - {}} } } {} ions which can also bind to Co(II), so the pH is adjusted close to 7 first by adding HNO 3 size 12{ ital "HNO" rSub { size 8{3} } } {} . (Other acids would introduce new ligands to compete for the Co.) NaNO 2 size 12{ ital "NaNO" rSub { size 8{2} } } {} is added to provide the ligands that will be trans in the final compound. Lastly, Co(II) is oxidized to Co(III) by bubbling oxygen through the solution.

Experimental procedure

  • Use your 10 mL graduated cylinder to measure out 20 mL of the 20% by weight solution of ethylenediamine in dilute HNO 3 size 12{ ital "HNO" rSub { size 8{3} } } {} .
  • Pour it into a clean 125 mL Erlenmeyer flask. Rinse the graduated cylinder with about 5mL of deionised water (DI water from white handle faucet) and add the rinse water to the flask. Set this aside for a moment and prepare the second set of reactants as described below.
  • Weigh out 9.0 g of hexaquacobalt(II) nitrate and 6.0 g sodium nitrite ( NaNO 2 size 12{ ital "NaNO" rSub { size 8{2} } } {} ) using a rough balance (Record mass on report form). Add these reactants to approximately 15 mL of DI water in an Erlenmeyer flask. After they have dissolved, add the neutralized ethylenediamine solution prepared in steps 1-2. Record your observations.
  • For the next set of instructions, refer to the diagram below. Fit a piece of rubber tubing over an inert gas "IG" tap (on benchtop) and open the valve slowly to obtain a gentle flow of oxygen. Then insert a Pasteur pipet into the other end of the rubber tubing. CAUTION: Too high a gas flow might blow the pipet out of the tubing and cause serious injury. Always adjust the valve carefully while pointing your pipet in a safe direction. Test the flow by immersing the pipet tip in a beaker of water--it should bubble vigorously, but not enough to cause much splashing. When the flow is set to your satisfaction, immerse the tip of the pipet in the Erlenmeyer flask containing the reaction mixture. Secure the flask to a stand with a clamp because the reaction mixture may need about 10 minutes of moderately vigorous bubbling to reach completion. Record your observations.

Questions & Answers

how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
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Do somebody tell me a best nano engineering book for beginners?
s. Reply
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Devang Reply
are you nano engineer ?
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
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so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
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s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
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Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
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I'm interested in nanotube
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preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
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silver nanoparticles could handle the job?
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I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
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Prasenjit Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
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Source:  OpenStax, Honors chemistry lab fall. OpenStax CNX. Nov 15, 2007 Download for free at http://cnx.org/content/col10456/1.16
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