FINAL REPORT

INORGANIC LABWORK

SYNTHESIS cis-K[Cr(H2O)2(C2O4)2] AND trans-K[Cr(H2O)2(C2O4)2]

BY :

Name : Zulvana Anggraeni Harvian

Number of student : 12/327756/PA/14373

Day,Dates : Tuesday, 9 March 2015

INORGANIC CHEMISTRY LABORATORY

FACULTY OF MATHEMATICS AND NATURAL SCIENCES

UNIVERSITAS GADJAH MADA

YOGYAKARTA

2015

RATIFICATION PAGE

LABWORK REPORT

SYNTHESIS cis-K[Cr(H2O)2(C2O4)2] AND trans-K[Cr(H2O)2(C2O4)2]

Has been prepared and compiled by

Zulvana A. Harvian

12/327756/PA/14373

Has been collected and checked by Assistant

on May 19th

2015

Assistant Practicant

Benny Wahyudianto Zulvana A. Harvian

SYNTHESIS cis-K[Cr(H2O)2(C2O4)2] AND trans-K[Cr(H2O)2(C2O4)2]

ZULVANA ANGGRAENI HARVIAN

12/327756/PA/14373

ABSTRACT

This experiments aimed To study the manufacture and properties of cis and trans

isomers of the complex salt K[Cr(H2O)2(C2O4)2]

K[Cr(H2O)2(C2O4)2] complex ion prepared by reacting oxalic acid with a

colorless crystalline solid orange crystalline potassium dichromate. Differences in the nature of cis and trans isomers K [Cr(H2O)2(C2O4)2] is the reaction with

aqueous ammonia. Trans isomer is not soluble in aqueous ammonia and produce

light brown precipitate. Whereas the cis isomer is soluble in aqueous ammonia to

produce a dark green solution which spread rapidly on filter paper. The yield that

obtained as long as the same structure were 70.17% and 66.88%.

Keyword: K[Cr(H2O)2(C2O4)2]ion complex

SYNTHESIS cis-K[Cr(H2O)2(C2O4)2] AND trans-K[Cr(H2O)2(C2O4)2]

I. THE AIMS OF EXPERIMENTAL SESSION

To study the manufacture and properties of cis and trans isomers of the

complex salt potassium dioxalatodiaquochromate (III)

II. THEORITICAL BACKGROUND

Based on the type of geometric isomer compound or complex ions

can be divided into types of cis and trans. To the complex there are two

types of octahedral complexes have cis and trans forms, namely

MA4B2 and MA3B3. M is an atom or ion center while A and B is a

monodentate ligand.

1. MA4B2 Type

2. MA3B3 Type

If the monodentate ligand is replaced with multidentate, for

example bidentate, it will produce a complex tie ML2B2. L is a

bidentate ligand. Isomer structure becomes:

A complex mixture of cis and trans forms may be prepared by

mixing the components of non-complex (complex compilers). Based

on the solubility difference between the cis to trans form the two types

of isomers that can be separated. For example, trans-

dioxalatodiaquochrom (II) chloride can be crystallized slowly with

evaporation of a solution containing a mixture of cis and trans forms.

With the evaporation equilibrium cis and trans forms can be shifted to

the right because of the lower solubility of the trans isomer. In

addition, the separation of cis and trans isomers can be done by

arranging conditions such that the complex solution laruta cis and trans

distinct, complex cis-dichlorobis (triethulstibin) palladium can be

crystallized in a solution of benzene though only 6% solution of cis

form.

Below the reaction in terms of nitrite ions, NO2 with

tetrachloroplatinate complex ion (II):

From the foregoing reaction can be said that the nitrite ligand has a

stronger trans effect than the chloride ligands. Trans effect strength of

several ligands can be sorted as follows:

I

III. RESULT AND DISCUSSION

III.1 Table of Result

Name Weight

Rexy & zul 2.6753 g

Iin & Nina 2.8071 g

Table 1 : Table of Result

III.2 Discussions

In an experiment aimed to study the manufacture and properties

of cis and trans isomers of the complex K[Cr(H2O)2(C2O4)2].

Divided into two groups that have been working on two different

circuits. The first group worked on every step of the experiment to get

the trans structure and the second group do to get results cis structure.

Structure is expected to come under this:

In making cis-K [Cr(H2O)2(C2O4)2], was observed by mixing solid

oxalic acid with a colorless crystalline solid orange crystalline

potassium dichromate, with treatment covered and only drops by a few

drops of distilled water, after a while become blue-black precipitate

and the resulting gas, the reaction is exothermic because the cup was

hot. Only the desired complex compounds containing two molecules of

H2O and 2 C2O42- molecules as ligands, so that if the solution still

contains a lot of H2O .H2O ligand possibility to increase in numbers

(more than chill). For that carried evaporation. The reaction is as

follows:

[ ]

Cis K [Cr(H2O)2(C2O4)2] with a final weight of 2.6753 grams. In order

to obtain% yield and yield are as follows:

Yield calculation :

Yield = (Weight observed / total weight) x 100 %

Yield = 66.88%

Percent results obtained only less than 90% of theoretical weight, due

to the potassium chromate is not mixed with oxalic acid. In addition it

is also possible for crystals that were lost during the storage process.

Obtained results are not in line with expectations in the manufacture of

trans-K [Cr(H2O)2(C2O4)2], the results of which should be obtained by

the procedure similar to the manufacture of cis structure are identified

by blending with ethanol is jet black color or viscous , The process of

color change from white to orange and black is due to the formation of

complex compounds of K [Cr(H2O)2(C2O4)2], in which the two kinds

of complex compound ligands and the central atom of the transition

metal. But it is obtained the same result by making cis. With the same

reaction but just a different structure. So the yield that obtained

70.17% were not so far from the result of cis- making.

Crystalline compound derived from experiments, placed on filter

paper. Then drops of aqueous ammonia. Ammonia (NH3), as well as

water binding oxalate or chromium, also a ligand. The addition could

substitute oxalate ligand or water. Consequently, in experiments on

crystalline complex, there is a section in the form of dark green

solution that quickly spread evenly. This part is called a cis potassium

dioksalatodiakuokromat. As for the potassium trans

dioksalatodiakuokromat, crystal drops of ammonia will form a solid

brown insoluble.

Clearly visible on the filter paper containing crystals of the complex.

Reactions that occur in the purity test is:

2K [Cr(C2O4)2(H2O)2] + 2NH3 2K[Cr(NH3)2(H2O)2]

The difference can be explained by the effect of the strength of the

order of ligand trans effects, namely: H2O

CALCULATION

Yield = (Weight observed / total weight) x 100 %

Trans : (actually same result as cis- product)

Cis :