March 31st 2015EXPERIMENT VSYNTHESIS OF TETRAAMINCOPPER(II)SULPHATE

A. Objectives1. Study the synthesis of complex salt tetra amin copper (II) sulphate as a result of the reaction between ammonia and cupri sulphate.2. Study the properties of complex salt tetra amin copper (II) sulphate.B. Theoretical BasisTheory coordination of Warner is the basis for coordination chemistry. This theory basing their secondary valence may explain the properties and stereochemistry of many complex compounds. However, with the development of the theory of atom deep perverse modern and the fact that Warner's theory can not explain many properties of complex compounds, arise new theories of coordination chemistry.Bond theory in complex compounds originally given by Lewis and Sidgwik. This theory because it can not explain the geometric forms of the compounds was later abandoned. Three theories that then arises is:a. Valence Band Theory (VBT)b. Crystal Field Theory (CFT) andc. Molecular Orbital Theory (MOT)(Sukardjo, 1985)Transition metals can form complex ions are diverse. An example is copper. Copper is a metal pink, soft, malleable, and clay. Copper melts at 10380C. Due to the positive standard electrode potential (+0.34 V for couples Cu / Cu 2+), copper is not soluble in hydrochloric acid and dilute sulfuric acid, although the presence of oxygen can dissolve a little copper. Salts of copper (II) anhydrous, such as Copper (II) Sulfate Anhydrous CuSO4, white (or slightly yellow). In aqueous solutions always contained tetraakuo complex ion (G. Svehla, 1990).Copper (Cu) is one of the lightest metal and the least active. Cu+ experience disproporsionisasi spontaneously at standard state (default). This does not mean the compound solution of Cu(l) not be formed. To assess the state of how the Cu (l) and Cu (lI) is formed, which is made (Cu+) enough in many water solution, Cu 2+ will be in large quantities (because its concentration should be about two million multiplied by the square of the Cu2+). Disproporsionisasi this would be perfect. On the other hand if the Cu+ kept very low (as in the slightly soluble substances or complex ions steady). Cu2+ is very small and copper (I) to settle.The addition of aqua ligands in solution causes the formation of complexes with the exchange of water molecules sequentially with NH3. For example, species [Cu(NH3)(H2O)5]2+ [Cu(NH3)4(H2O)2]2+ is formed in the normal way, but the addition of the fifth and sixth NH3 molecules difficult. Sixth molecules can only be added only in liquid ammonia (Cotton and Wilkinson, 1989).Synthesis of complex compounds can be performed by various methods, depending on the existing system but not all methods can be used for the synthesis of a complex. The commonly methods used in the synthesis of complex compounds is through the substitution reaction (replacement). This method involves the reaction between a metal salt in an aqueous solution (Mn+) with the coordination agent (ligand) in which an exchange/explacement of the ligand. For example , the manufacture of [Cu(NH3)4]SO4 can be done by mixing a solution of CuSO4 in water with NH3 through the reaction :[Cu(H2O)4]2+(aq) + 4NH3(aq) [Cu(NH3)4]2+(aq) + 4H2O(l)Dark blueComplex of salt [Cu(NH3)4]SO4 is dark blue crystals that is formed on the addition of ethanol. Synthesis of complex compounds through recrystallization can be done with some of the following techniques : Evaporate the solvent and cooling the reaction mixture becomes more concentrated in a water-bath containing a salt-ice. Slowly add solvent that can be mixed with solvent of reaction mixture, but not dissolving the desired compound. If the desired cation complexes can be isolated by adding the appropiate anion, so it will form an insoluble salt, and instead of a cation can be added to the reaction mixture to precipitate the anion.(Inorganic Chemistry Lecturer Team, 2015)C. Equipment and MaterialEquipment :1. 50 ml volumetric flask2. 100 ml beaker3. 1 set of vacuum pumps4. Filter paper5. A small test tube6. 1 set buchner heating7. 1 large test tubeMaterial :1. Crystal of CuSO4.5H2O2. Concentrated ammonia3. Ethyl alcohol 96%D. Work Instruction1. Synthesis of tetra ammin copper(II)sulphate complex2.5 g CuSO4.5H2O weighed and then dissolved in 5 ml H2O in a glass beaker

12.5 ml of concentrated NH3 10% added, stirred it until homogeneous

4 ml of 96% ethyl alcohol added in the walls of the beaker. Dont be stirred or shaken

Covered with a watch glass and allow it for 1 hour

Let stand and store it in refrigerator for overnight to crystallize

Crystals are separated by filtration

Crystals are washed with 4 ml of concentrated ammonia mixture with ethyl alcohol (1:1)

The crystals are dried

The dry crystals are weighed

Experiment 2. Study the properties of the complex salt tetrammincoppere(II)sulphateA little salt dissolved from step q of experiment in 5 ml H2O, the color is observed

The solution dillute with 20 ml H2O, the color change is observed

Aof dry salt placed in a test tube and reheat slowly. The color change is noted. Observed the gases released

E. Result of ObservationThe mass of CuSO4.5H2O = 2,5 gramMr CuSO45H2O = 249,5n CuSO4.5H2O = = = 0.0100 molReaction (adding water)CuSO4.5H2O(s) + H2O(l)Cu(H2O)4SO4(aq) + 2H2O(l)m0.0100 mol0.0100 mol00r0.0100 mol0.0100 mol0.0100 mol0.0200 mols000.0100 mol0.0200 molReaction (adding NH3)Cu(H2O)4SO4(aq) + 4NH3(aq)Cu(NH3)4SO4(aq) + 4H2O(l)m0.0100 mol0.0400 mol00r0.0100 mol0.0400 mol0.0100 mol0.0400 mols000.0100 mol0.0400 molMr Cu(NH3)4SO4 = 227,5 The theoritical mass of = = = 2,2750 gramRendement= x 100%= x 100%= 78.40%F. DiscussionSynthesis of tetraamincopper(II) sulphate experiment has crystallization and recrystallization methode. Crystallization is to separate by forming crystals, recrystallization is to purify the precipitate.1. Synthesis of tetraamincopper(II)sulphate complexPracticant must prepare CuSO4.5H2O crystals and NH3 to synthesis it. The color of CuSO4.5H2O is blue and it is solid, practicant must dissolve it with aquadest. Aquadest have big dipol moment, so CuSO4.5H2O can dissolve. But it is dificult to dissolve, it must stirring for many times. This hydrat still in one ion species. When dissolve in aquadest, the solution has blue color. Blue color of solution because there are Cu2+ ion. Look at this reaction :CuSO4.5H2O(s) + H2O(l) [Cu(H2O)4]SO4(aq) + 2H2O(l)Based on reaction, we know that aquadest pull H2O in crystals to form solution. The solution will be produced [Cu(H2O)4]SO4 is a complex salts.After that, NH3 concentrated put into the solution, this process do in acid cupboard because NH3 concentrated will produce sting gases. The gases is dangerous for practicant, so we need safety our self.Stir it quickly after added NH3 and cover it by ethyl alcohols slowly. In order to save NH3, that because of NH3 is easily to evaporate. If much NH3 evaporate, so H2O in [Cu(H2O)4]SO4 cant remove and opportunity for producing crystals is little. The function of adding NH3 is to push H2O ligand. NH3 is strong ligand and H2O is weak ligand, so NH3 can push easily. NH3 remove H2O from [Cu(H2O)4]SO4, the complex become [Cu(NH3)4]SO4. Strong ligand make the color become more darken. The solution after this reaction is dark blue - purple. Look at this reaction :[Cu(H2O)4]SO4(aq) + 4 NH3 (aq) [Cu(NH3)4]SO4(aq) + 4 H2O(aq) Then closed with plastic, in order to the gases are not dissapear and crystals formed maximally. We need 1 hours to waiting it. It can prevent vapourization of some ions, and for forming monoclin crystal perfectly too.After that the solution save in refrigerator along 3 days. Low temperature make solubility decrease and crystals can formed. Observe the result after 3 days. There are crystals have dark blue color. But there still little solution. To purify this solution wash with mix solution (NH3 concentrated with ethyl alcohol). Washing solution can increase the mass of crystals, because washing can separate crystals from another substance. The crystal dried use oven until dry for 15 minutes, so the result of crystals is purify crystals not contain water or another substance. After weighing the mass of tetraamincopper(II) sulphate are 1,7836 g. Based on theory the mass of crystals is 2,2750 g. From that data, the rendement of tetraamincopper(II) sulphate is 78,40%. From that we know it still not maximally because occurs some mistakes, there are: When dissolve CuSO4.5H2O with aquadest this still not dissolve perfectly, because in fact CuSO4.5H2O very difficult to dissolve. Adding ethyl alcohols not enough slowly, it makes the solution not cover be spreed evenly. Covering use plastic not enough quickly, so NH3 was evaporate.2. Study the properties of the complex salt tetrammincopper(II)sulphateThe complex salt of tetraamincopper(II)sulphate has some properties. To know that, it must test. The test has to point there are adding aquadest and heating need to test it.First test, aquadest 5 ml pour into the salt of tetraamincopper(II)sulphate. The result of it is the salt dissolve and the color of solution is dark blue. Then add aquadest 20 ml, so the color of solution is light blue. Based on that we know, color of solution become more light when we add aquadest much. They are different because there are also different to adsorb the wave long of visible light. Only one color adsorbed, so we can look complementer color of it. Look at this reaction :Cu(NH3)4 SO4(s) + H2O Cu2+(aq) + SO42-(aq) + 4NH3(g)Second test use heating, the complex salt of tetraamincopper(II)sulphate pour into test tube and heated. The color of salt become green. G. Question1. Write down all the reactions that occur in the synthesis of tetraamin copper(II) sulphate !2. What is the function of alcohol on the redox reaction ?3. Mention some tetraamin copper (II) sulphate use of !4. What type of ion that exists when tetramin copper (II) sulphate salt is dissolved in a little water and how changes that occur when dissolved in excess water ?5. How do the properties of this complex salt ?Answer :1. CuSO4.5H2O(s) + H2O(l) [Cu(H2O)4]SO4(aq) + 2H2O(l)[Cu(H2O)4]SO4(aq) + 4 NH3 (aq) [Cu(NH3)4]SO4(aq) + 4 H2O(aq)Cu(NH3)4 SO4(s) + 2H2O(l) [Cu(H2O)2(NH3)4]2+(aq) + SO42-(aq)2. Function of alcohol on the redox reaction is to save NH3 in order to not evaporated, so crystals forming.3. Analysis forming crust in pipe4. Cu2+ and SO42-5. The properties of complex salt tetraamincopper(II) sulphate in this experiment are about adsorbtion the wave long of visible light and oxidation reaction.H. Conclusion1. Synthesis of tetraamincopper(II)sulphate can produce use cupri sulphate and ammonium with the specially process (there are adding ethyl alcohols, waiting, refrigerating, washing, and drying.2. The properties of complex salt tetraamincopper(II) sulphate in this experiment are about adsorbtion the wave long of visible light and oxidation reaction.3. Rendement of [Cu(NH3)4]SO4 is 78,40 %.I. Suggestion1. When adding ethyl alcohols must slowly, it makes the solution covered be spreed evenly.2. We must covering use plastic quickly, so NH3 was not evaporate.3. Reagents must steril from contaminated.4. The litmus papper must keep from contaminated, so can use to know acid/base.

J. Refference

Cotton and Wilkinson. 1989. Kimia Anorganik Dasar. Jakarta: UI-Press.Inorganic Chemistry Lecturer Team. 2015. Manual Work of Inorganic Chemistry Practicum. Semarang : UNNES.Sugiyarto. 2003. Dasar-dasar Kimia Anoraganik Logam. Jakarta : UI-Press Sukardjo. 1985. Kimia Koordinasi. Jakarta: PT. Bina Aksara. Svehla, G. 1990. Vogel : Buku Teks Analisis Anorganik Kualitatif Makro dan Semimikro Bagian I Edisi Kelima. Jakarta: PT Kalman Media Pusaka.