Complex Salt.docx

COMPLEX SALT

1. Preface 1.1 Objective Study about reaction of making complex salt tetramincopper (II) sulphate hydrate [Cu(NH3)4]SO4.xH2O. 1.2 Introduction A double salt is a salt formed by crystallizing a mixed solution of an equivalent amount of two or more specific salts. A double salt is formed when two salts crystallize together with a certain molecular ration. The salts have their own structure and should not be the same as the component salts structure. A complex salt is a salt formed from an anion or a complex cation, for example [Co(NH3)6]3+ and [Fe(CN)6]3-, otherwise known as a coordinating compound. Example potassium hexacyanoferrat(III) or K3[Fe(CN)6]. Copper is a light-red metal, which is soft, malleable, and ductile. It melt at 1038o C. Because of its positive standard electrode potential ( +0.34 V for the Cu/Cu2+ couple) it is insoluble in hydrochloric acid and in dilute sulphuric acid, although in the presence of oxygen some dissolution might take place. There are two series of copper compound.

Copper(I) compounds are

derived from the red copper(I) oxide Cu2O and contain the copper(I) ion Cu+. These compounds are colorless, most of the copper(I) salts are insoluble in water their behavior generally resembling that of the silver(I) compounds. They are readily oxidized to copper(II) compounds, which are derivable from the black copper(II) oxide, CuO. Copper(II) compounds contain the copper(II) ions Cu2+. Copper(II) salts are generally blue both in solid, hydrated from and in dilute aqueous solution; the color is characteristic really for the tetraquocuprate(II) ion [Cu(H2O)4]2+ only (Vogel, 1979). One of the properties of the transition element is that it has a tendency to form complex ions or complex compound. Ions of transition metal elements

have empty orbitals that can accept electron pairs in bonding with certain molecules or anions to form complex ions. Complex ions composed of central metal ions surrounded by anions or molecules forming a coordination bond. Central metal ions are called central ions or central atoms. Anion or molecules that surround the central ions are called ligands. The number of coordination bonds between central ions and ligands is called coordination number. The central ion is the transition element ion, can receive the free electron pair form the ligand. Free electron pair from ligand occupy empty orbital in subshell 3d, 4s, 4p and 4d in central ions. Ligand are molecules or ions that can donate free electron pairs to central ions. Ligand are neutral and negatively charged or positive. Naming ligand adjusted to the type of ligand. When there are two kinds of ligands or more then sorted alphabetically (Maulana, 2007). 2. Methods 2.1 Apparatus and Reagent Apparatus In this labwork we using many apparatus to prepare the complex salt that will be characterize. There are beaker glass 50 mL, graduated cylinder 50 mL, volumetric pipet with pipet filler bulb, analytical balance, dropping pipet, watch glasses, filter paper, aluminium foil, oven, and funnel. We also using an instrument for test; FT-IR spectrometer, Conductivitymeter, and UV-Vis spectrophotometer. Reagent The reagent that using is CuSO4.5H2O crystal, (NH4)2SO4 solution, concentrated ammonia, ethanol, aquadest, and KSCN 0.5 M. 2.2 Skema Kerja Preparation of Complex Salt

1.25 grams of copper(II) sulphate pentahydrate diluted by 5.0 mL aquadest in beaker glass 50 mL

solution added by dropping excess concentrated ammonia until the precipitation dissolved again

Close the beaker glass with aluminium foil and left at room temperature, obseve the crystal formation in next day

the crystal or precipitate filter and put off watch glasses. Dried crystals in the oven at  60o C for 2 hours, then weighed

added 20 mL ethanol through the glass wall until two layer formed (bottom = dark blue, top = clear)

Test or Characterizing

measuring the absorbance spectrum. The complex salt dissolved by 10 mL aquadest. Then, 2 mL of this solution react with 1 mL KSCN 0.5 M.

measuring conductivity. For the comparative solution, we used NaCl solution, CuSO4 solution, and FeCl3 solution each with concentration 0.025 M.

FT-IR spectrophotometer. A small amount of the obtained complex salt is placed on the sample holder ATR-FTIR.

2.3 Procedure Preparation of Complex Salt First step, 1.25 grams of copper(II) sulphate pentahydrate diluted by 5.0 mL aquadest in beaker glass 50 mL. For weighed the copper(II) sulphate pentahydrate mass, we using analytical balance.

Second step, the solution added by concentrated ammonia dropping until precipitate formed. Then, addition excess of concentrated ammonia until the precipitation dissolved again. Third step, added 20 mL ethanol through the glass wall until two layer formed (bottom = dark blue, top = clear). Close the beaker glass with aluminium foil and left at room temperature, obseve the crystal formation in next day. For last, the crystal or precipitate filter and put off watch glasses. Dried crystals in the oven at  60o C for 2 hours. Then, the crystal that formed weighed using analytical balance. Test or Characterizing There are 3 type of test or characterization. That is FT-IR spectrum, UVVis spectrum, and conductivity test. For the measuring the absorbance spectrum at 300-800 nm, first we weighed a number of mass from complex salt. The complex salt dissolved by 10 mL aquadest. Then, 2 mL of this solution react with 1 mL KSCN 0.5 M. Observe the change that happen and measure absorbance spectrum at 300-800 nm. The second test is measuring conductivity. For the comparative solution, we used NaCl solution, CuSO4 solution, and FeCl3 solution each with concentration 0.025 M. To measuring the IR spectrum of complex salt, we using FT-IR spectrophotometer. A small amount of the obtained complex salt is placed on the sample holder ATR-FTIR. 3. Results and Discussion 3.1 Results Procedure

Observation

1

Diluting 1.25 gram copper (II) sulphate  pentahydrate in 5.0 mL aquadest   

2

Addition of conc. Ammonia precipitate formed dissolved again

3

Addition ethanol through the glass wall  Vethanol : 20 mL until formed 2 layer  Top layer : clear solution  Bottom layer : dark blue

4

Close the beaker glass with aluminium  Precipitate color : dark blue foil and observe the crystal formation  Storage time : 2-3 days  Vsolution :  35 mL

5

Filter and put on the watch glasses, then  Oven temperature :  60o C dried crystals in the oven. And last,  Oven time : 2 hours weighed  Crystal color : dark blue  Crystal weight = mtotal – mwatch glasses = 21.6585 g – 21.3155 g = 0.343 gram

Mass of CuSO4.5H2O : 1.2540 gram Balance specs : analytical Vaquadest : 5.0 mL Solution color : blue

until  Precipitate color : light blue  Vammonia : 49 dropped  Solution color : dark blue

Conductivity Test Msampel

= =

𝑀𝑎𝑠𝑠 𝑀𝑟

𝑥

0.1556 317.5

1000 𝑚𝐿

𝑥

1000 50

= 0.0098 M Because the molarity of sample solution different with comparative solution, so the comparative solution is dilution; V1 . M1 = V2 . M2 V1 . 0.25 = 50 (0.0098) V1 =

50 (0.0098) 0.25

= 1.96 mL The results of conductivity test at T = 27.9o C; No

Solution

Conductivity

1

Water

2.00 µs

2

CuSO4

609 µs

3

NaCl

637 µs

4

FeCl3

2.01 ms

5

Complex salt

931 µs

3.2 Discussion Analysis Data a) Mass of CuSO4.5H2O

= 1.2540 gram

Mass result [Cu(NH3)4]SO4 b) Mole of CuSO4.5H2O

= =

= 0.3437 gram 𝑀𝑎𝑠𝑠 𝑀𝑟 1.2540 249.5

= 5.026 x 10-3 mol c) Mole NH3,  = 0.899 g/mL If we assume that 2 drop is 1 mL, so 49 drop = 24.5 mL Mass of NH3

=xV = 0.899 g/mL x 24.5 mL = 22.0255 gram

Mole of NH3

=

22.0255 gram 17,031 g/mL

= 1.2932 mole

d) Reaction between CuSO4.5H2O and NH3

[Cu(H2O)5]SO4

+

4 NH3

[Cu(NH3)4]SO4

+

5H2O

m

0.0050

1.2932

r

0.0050

0.0200

0.0050

0.0250

s

-

1.2732

0.0050

0.0250

e) Mass of [Cu(NH3)4]SO4 = mol x Mr = 0.0050 mol x 227.5 gr/mol = 1.1375 gram f) Rendemen =

=

practical weight theoretical weight 0.3437 gram 1.1375 gram

x 100%

x 100%

= 30.215 % In the process make complex ion begins by reacting CuSO4.5H2O with a ammonia solution with stirring until all crystal dissolve, result blue solution. This reaction causes a stinging gas that comes from concentrated ammonia. Ethanol classified as a volatile solvent, as well as other alcoholic properties. Therefore, after the addition of ethanol, the glass is directly covered with aluminium foil to reduce evaporation during the formation of crystals. This salt formation process takes a long time to form a perfect crystal. After the crystal formed do the filtration for separated the crystal from solution and washed. The resulting crystals are blue and the mass of the complex salt crystals is obtained 0.3437 grams. 4. Closing 4.1 Conclusion 

The complex tetramincopper(II) sulphate can made by reacting CuSO4.5H2O with ammonia solution



The ammonia, NH3, replacing the H2O position as a ligand in the central aton.



The mass of crystal that obtained is 0,3437 grams

4.2 Suggestion 

In the making complex ion process, the position of the beaker glass should not be rocking



Prepare the theory before do labwork



Wisely in do procedure

5. Bibliography Effendy, 1996. Sintesis dan Struktur Senyawa-Senyawa Kompleks Logam-logam Alkali Tanah. Media Komunikasi Kimia, Vol 1, No 2. Maulana, 2007. Senyawa atau Ion Kompleks. http://masterkimia.com Vogel, 1979. Textbook of Macro and Semimcro Qualitative Inorganic Analysis. Longman Group Limited. London. 6. Appendix