Metals are rarely found in nature in the form of the element, but in the form of compounds. Metal is a compact and stable arrangement. General nature of the metal is large thermal conductivity, can be forged, and large electrical conductivity. Required the existence of certain methods to separate and determine the metal content of certain compounds.
Separation of metal ions was determined using specific reagents. For example, 8-hidroksiquinolin known oksin trivial. This reagent forms a neutral molecule, are not polar, insoluble in water but very soluble in organic solvents such as benzene, solvents, alcohol, and others. The principle of organic reagents with certain metal ions can form complex compounds with organic high molecular weight.
Determination of metal content in the compound that underlies this experiment done, we will discuss about settling compounds react with the metal. Some commonly used organic reagent dimetilglioksin ie, α-benzeinoksin, kupferron, 8-hidroksiquinolin, and Anthranilic acid. Metals used in these experiments was an iron, while the compounds used pengendapnya oksin or 8-hidroksiquinolin.
For more details, the thing that lies behind this experiment was conducted to know the deposition that has happened and use the results of the reaction to determine the metal content oksin formed with the reagent.
1.2 Experiment Objectives
1.2.1 Purpose Experiment
The purpose of this experiment is to study the reaction of metal cations with the reagent oksin.
1.2.2 The purpose of Experiment
The purpose of this experiment was to determine the metal content of Fe concentration or by using the reagent oksin.
1.3 Principle Experiment
The principle of the experiment is to determine the concentration of iron metal with a compound oksin through sedimentation and filtration processes, where the sediment filtered and cleaned of contaminant substances was dissolved with hot HCl and then titrated using KBrO 3 and Na 2 S 2 O 3 to determine the Fe content in the solution.
One way is called titrimetry chemical examination, which checks the number of substances which are based on measuring the volume of reagent solution required to react stoichiometrically with the specified substance. In one sense this way is profitable because its implementation is easy and fast, precision and accuracy is high enough. In another aspect, this method is advantageous because it can be used to determine levels of various substances that have different properties (Rival, 1995).
For the addition of a thrifty solution used burette, which is a glass tube tera marked for volume and spout to regulate fluid can flow out to fast or slow drips as necessary. A way that is much more accurate titration is called gravimetric titration (Harjadi, 1986).
Titration is a careful penbambahan volume of a solution containing a known concentration of substance A, the second solution containing a substance B that concentration is not known, which will result in both a quantitative reaction. The completion of reaction, ie at the end point. In most acid-base reaction, no color change at the sharp end point. In this case the need to add a little indicator, ie dyes that change color when the reaction is complete (Oxtoby, 2001).
Titration can be performed without the indicators from the outside because the color will disappear when titrated endpoint is reached. When considered carefully these color changes, m the end point can be determined clearly. But is easier and more assertive when added into the starch solution as indicator. The addition of this starch should be close to the end point titration. The point is to not wrap the starch grains and causes difficult yod off again (Harjadi, 1986).
In addition there are also chemical properties physical properties of the metal and most of nature include the following characteristics (Keenan, et al., 1989):
Resource type high electrical conductivity.
Conductivity type high heat.
Mengkilapnya surface, gray or silver.
The ability to change shape without cracking if given a voltage.
Can be forged and melted even the atoms that exist at each other they are strong.
The physical properties of a metal called stating that the bond valence bond that binds the atoms that are not ionic bonds, covalent bonds are also not simple and also despite the metal atoms and usually only have one or up to four outer electrons. According to current views, a metal consists of a tight lattice derived daari positive ions and there is the atmosphere surrounding valence electrons. Valence electrons are confined to certain energy surfaces. However, they have coverage freedoms so that they are not constantly used jointly by the two ions that remain the same or in other words that it was too ion. When given energy, electrons are easily transferable from atom to atom, this bond is a unique system for bonding metals and is known as a metal and not a simple ionic or covalent (Keenan, et al., 1989).
Many derivatives of quinoline alkaloids are found in the plant kingdom. In such polynuclear compounds, the more highly activated aromatic ring will from be attacked by an electrophile. Oxidation is similar with only the more highly activated aromatic ring being cleaved by the oxidant (Fogiel, 1995).
Many alkaloid derived from kuinolin found in plants. Like polinukleotida compounds, the most active aromatic ring attacked by electrophiles. Oxidation with the most active aromatic ring by an oxidant (Fogiel, 1995).
It can also affect the precipitation reactions such as the nature of the metal itself where it concerns the nature of its physical properties, chemical properties. Chemical properties of a metal, mostly as an electron donor in reactions of metal ions is usually a positive ion. This is attributed to the low ionization energy of metal atoms and the fact that there are usually less than four electrons in its outer energy levels (Keenan, et al., 1989).
Compounds with molecular formula C 9 H 7 ON oksin known, none other than 8-hidroksiquinolin with a molecular weight 145 g / mol. Structural formula of this compound are:
Oksin is a compound with a form of white crystals that melt at a temperature of 74-76 o C. These compounds are difficult to dissolve in water and in ether, but soluble both in alcohol, chloroform, and benzene. With a little water, which initially colorless solution will change into yellow (Hala, 2008th).
Oksin reaction is one of settling for many metals. Divalent metal or trivalent which has been deposited by oksin, can be described in such general form: M (C 9 H 7 ON) 2 and M (C 9 H 7 ON) 3. Reaction with metals and trivalent metals can oksin presented in the form of the scheme as follows:
Results obtained from the reaction of the merger process between metal cations with oksin is an internal complex compounds are not soluble in water. This complex has a value of solubility product (KSP) of approximately 10 -12 and 10 -12. As a result, these compounds can be used as settling on the value of different pH can be done so that the separation of a mixture of metals contained in the sample (Hala, 2008).
The materials used in these experiments that iron (Fe) 100 ppm, oksin 2% solution in alcohol, 0.1 M sodium acetate, 0.1007 N KBrO 3, HCl (hydrochloric acid), 4 M, 2 M HCl, sodium thiosulfate 0 , 1003 M, 0.5 grams of KBR (potassium bromide), KI (potassium iodide) 10%, methyl orange indicator, 1% starch indicator, tissue roll, distilled water, filter paper Whatmann 42, a universal pH indicator paper, and soap.
The tools used in these experiments was 400 mL beaker, 250 mL beaker, 50 mL beaker, glass funnel, stirrer shaft, thermometer 100 o C, 50 mL burette, stative, 25 mL measuring cup, measuring cup 10 mL , bulbs, hyacinth 20 mL pipette and 10 mL pipette drops, Ohauss balance sheet, spoon horn, electric heaters, asbestos gauze, cover the cup, pumpkin spray, and 250 mL erlenmeyer.
3.3 Experimental Procedure
1. Dipipet solution of iron (Fe) 100 ppm of 20 mL into 400 mL beaker.
2. Added 70 mL of 0.1 M sodium acetate pH sehinggan reach 5.
3. Added dropwise oksin solution in alcohol 2% while stirring to precipitate.
4. Precipitate that formed was then heated several minutes at a temperature of 60-70 0 C, then filtered using Whatman 42 filter paper.
5. The precipitate was washed with hot water and sediment was dissolved with 50 mL 4 M hot HCl solution.
6. Then added 0.5 g of KBR and 2-3 drops of indicator MO.
7. Solution titrated with standard 0.1 N KBrO 3 to form a pale yellow color.
8. Solution diluted with 25 mL of HCl 2 M and about 2 minutes left in enclosed places.
9. Added 10 mL 10% KI solution and finally titrated with 0.1 N standard solution natriumtiosulfat and starch indicator until the yellow color formed.
RESULTS AND DISCUSSION
RESULTS AND DISCUSSION
In this experiment oksin reagent used is oksin dissolved in alcohol with a concentration of 2%. To determine the metal content is 100 ppm iron solution is then added with 111.9 mL of saline solution of sodium acetate 0.1 M, so that the pH of the solution to 6. PH measurements using a universal pH indicator paper. At the time of addition of sodium acetate solution color from clear to yellowish. Changes in color due to iron is the primary color of yellow. Oksin solution then poured the solution to precipitate the dark green, where the sediment is a complex formation of iron and oksin.
Deposition solution was then heated several minutes at a temperature of 60-70 0 C. Heating was conducted in order to dissolve the re-deposit that formed because the solubility increases when temperature is increased. After that, filtered using Whatman 42 filter paper and wash with hot water to dissolve the impurity-impurity or foreign substance contained in the sediment. After that, the precipitate was dissolved in hot 4 M HCl HCl function that is to wash the sludge contained iron in order to dissolve all of the filter paper. HCl can dissolve because HCl has a pH of precipitation is small. Then added KBR, the addition is intended to precipitate dissolved in HCl can be titrated with KBrO 3. And methyl orange indicator was also added, whereby the addition of this indicator gives orange color of the solution.
Solution and then titrated with 0.1007 N KBrO 3 is intended to determine the existing free bromine in solution. When titrated, the solution diluted with 18 mL of HCl 2 M. The purpose of this dilution to maintain the pH value of solution, then allowed approximately 2 minutes in a closed place to improve dilution. Then add 5 mL 10% KI solution. These additions have resulted in the solution a black precipitate.
Solution was titrated with sodium thiosulfate standard solution 0.1003 M, the color changed to yellow solution and starch indicator added dropwise until the end point is marked with a color change to pale yellow. Starch indicator function that is free of iodine binding in order to determine the achievement of the end point titration.
In this experiment, the titration done in recurrent intended to be obtained is more pure metal. Based percobaaan, found metal content of Fe in solution is -108.122%. This value does not match, should not be minus the value obtained in the calculation. This is possibly due to a lack of accuracy in performing titration and the solution used was contaminated with other compounds, so the results are not accurate.
CONCLUSIONS AND RECOMMENDATIONS
CONCLUSIONS AND RECOMMENDATIONS
Based on the above experiment can be concluded that the metal content of Fe in solution is -108.122%.
Metal should be practiced not just iron, but other metals can also order praktikan better understand and laboratories should also provide materials that are still pure and not contaminated.
assistant should have more control over when to experiment and explain the functions of the experimental treatment that may further deepen praktikan about this experiment.
Fogiel, M., 1995, The Organic Chemistry Problem Solver, Research and Education Association, New Jersey.
Hala, Y., 2008, Penunutun Practical Inorganic Chemistry, Inorganic Chemistry Laboratory, Science Faculty Hasanuddin University, Makassar.
Harjadi, W., 1986, Analytical Chemistry Basics, PT Gramedia, Jakarta.
Oxtoby. 2001. Principles of Modern Chemistry. Grants. Jakarta.Rivai, H., 1995, Principle of Chemical Examination, UI-Press, Jakarta
Rivai, Harrizul, 1995, Chemical Principles Examination, the UI Press, Jakarta.