# 0.9 Transition metals  (Page 2/3)

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$\left[{\text{CrCl}}_{2}\left({H}_{2}O{\right)}_{4}\right]\text{Cl}\cdot \left({H}_{2}O{\right)}_{2}\to \left[{\text{CrCl}}_{2}\left({H}_{2}O{\right)}_{4}{\right]}^{+}+{\text{Cl}}^{-}+\text{water}$

The light green compound with two reactive chlorines is apparently $\left[\text{CrCl}\left({H}_{2}O{\right)}_{5}\right]{\text{Cl}}_{2}\cdot {H}_{2}O$ , while the violet compound with three reactive chlorines is $\text{Cr}\left({H}_{2}O{\right)}_{6}{\text{Cl}}_{3}$ .

Closely related to hydrate isomerism is ionization isomerism, where an ion takes the place of water. Consider two different compounds with the formula $\text{Co}\left({\text{NH}}_{3}{\right)}_{5}{\text{SO}}_{4}\text{Br}$ . One of these, $\left[\text{Co}\left({\text{NH}}_{3}{\right)}_{5}\left({\text{SO}}_{4}\right)\right]\text{Br}$ , appears red, whereas the other, $\left[\text{Co}\left({\text{NH}}_{3}{\right)}_{5}\text{Br}\right]{\text{SO}}_{4}$ , 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 $\left({\text{NO}}_{2}\right)$ ligands. The geometrical isomer you will make is the trans form, in which the ${\text{NO}}_{2}$ 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 $\left({\text{NO}}_{2}\right)$ ligands specifically dinitrobis(ethylenediamine)Co(III). The two black balls represent the ${\text{NO}}_{2}$ 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 ${\text{NO}}_{2}$ ligands.

In the procedure that follows we start with a cobalt solution made from the salt hexaquacobalt(II) nitrate, $\left[\text{Co}\left({H}_{2}O{\right)}_{6}\right]\left({\text{NO}}_{3}{\right)}_{2}$ . When this salt dissolves it ionizes to form two ions of ${\text{NO}}_{3}^{-}$ and one of $\text{Co}\left({H}_{2}O{\right)}_{6}^{2+}$ . 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 ${\text{OH}}^{-}$ ions which can also bind to Co(II), so the pH is adjusted close to 7 first by adding ${\text{HNO}}_{3}$ . (Other acids would introduce new ligands to compete for the Co.) ${\text{NaNO}}_{2}$ 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 ${\text{HNO}}_{3}$ .
• 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 ( ${\text{NaNO}}_{2}$ ) 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.

Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
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.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
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