Using English to Report

COMPARISON OF THE COMPARISON OF ION COMPOUNDS AND CENTRAL COMPOUNDSI. THE OBJECTIVES OF EXPERIMENT

 The purpose of this experiment is to enable the practitioner to know and explain the effect of the bonding type of a compound on the physical properties and chemical properties of the compound.II. LITERATURE REVIEW
      II. 1 Chemical bondA chemical bond is a bond that occurs because of the attraction between the bonding particles. A highly electropositive element atom can release 1 or 2 electrons in its outer shell and an electronegative element atom can receive 1 or 2 electrons released by an electropositive element atom. The term polar is sometimes used as an elektrovalen term. According to Lagmuir, the compound formed by electron handling of the forming atoms is called an electrodeal compound or an ionic compound, and the bonding of the compound is called an electrotalene bond, or an ionic bond. At room temperature, the ionic compound is present in a crystalline form called ionic crystals. The ion crystals consist of positive ions and negative ions (Syarifuddin, 1994).According to Lewis, Langmuir, Kosel, an atom binds to other atoms and forms compounds, the atoms undergo such changes that have electron configurations that resemble electron configurations that resemble noble gas electrons (Syarifuddin, 1994).Elements that tend to receive electrons or their electronegativity values ​​≥ 2.0 are called electronegative elements. This element is located on the top and right of the block p on the periodic system and added hydrogen. The tendency of electronegative elements to receive electrons is due to the drive to achieve stability, so that valence electrons are like noble gases (Syukri, 1999).

      II.2 Difference of ionic compounds and covalent compounds

         Ionic bonds are bonds between positive ions and negative ions, which occur because particles of opposite charge will result in attraction between these ions. Positive ions and negative ions will be formed when electron transfer takes place between atoms (Syarifuddin, 1994).
         Two elements (one tends to release electrons and others tend to accept), when contact is not necessarily an ionic compound, because it depends on the energy level before and after the reaction. Ionic compounds are not simple, but they are gigantic molecules formed from positive and negative ions which are alternated regularly (Syukri, 1999).
         The tendency of ions to attract other electrons whose charges are opposite and to reject the same charge ions results in a regular arrangement of three-dimensional ions. The three main effects of ionic compounds are as follows:1. The ion charge2. Relative size of the two ions involved3. Ease of the ion for tedistorsi or polarized (Sukardjo, 1990)
         Ionic compounds formed from positive and negative ions are arranged alternately to form a giant molecule that will have certain properties, namely:1. Melting and boiling points, the attraction between positive and negative ions in the ionic compound is quite large, one ion binds to several ions with opposite charge. As a result, the melting point and boiling point of the ionic compound is higher.2. Solubility, in general, soluble ions in polar solvents (such as water and ammonia), since some solvent molecules confront their negative poles to positive ions, and some confront their positive poles to negative ions, eventually the ions are separated from each other)3. Electrical conduct, electric conduction occurs when the medium contains free-flowing charged particles, such as electrons in a metal bar, solid-state compounds, not conducting electricity, because negative and posittive ions are strongly bonded to each other. However, the liquid ion compounds will deliver electricity because the ions become loose and free. Ionic compounds may also conduct electricity, when dissolved in a polar solvent (eg water-like compounds) because they are ionized4. Hardness Because of the strong bond between the positive and negative ions, the ionic compounds are hard and crystalline solids, the surface of the crystal is not easily scratched or shifted (Syukri, 1999).A covalent bond is a bond that occurs between two atoms together. Bromine, carbon dioxide, Hexane, Amoia, and ethyl alohol are examples of covalent compounds. The melting and boiling point of the covalent compound tends to be lower than that of the ionic compound. This is due to the fact that to melt and vaporize a solid or molecular liquid requires only enough energy to generate the energy of Van der waals attraction between molecules (Audrey, 1991).
As a condition of molecular formation according to the theory of molecular orbitals is that the orbial involved in bond formation must contain only one electron. The two atoms to be bonded must have such a position that one orbitals filled with one electron overlap or overlap with the other. When this happens, the two orbitals join to form a single bonding orbitals occupied by two electrons. Two electrons occupying the orbital must have opposite spin directions, ie, paired. The larger the overlap of atomic orbitals, the stronger the bonds are formed. This bond is called seing covalent bond (Hardjono, 1987).One or more electron pairs are absorbed by both atoms. When these electrons circle the atoms, the electrons spend much longer between the two atoms, compared to other places, resulting in a tensile force. For example H2, a hydrogen molecule whose electrons are shared by both protons more than adequately equilibrate the surrounding immediate repulsions. If the protons are close together, their repulsion becomes dominant and the molecule is unstable (Arthur, 1987).The difference between ionic compounds and covalent compounds lies in:1. In ionic compounds, low melting point, sdangkan on high melting point covalent compound.2. The compound ion is soluble in water and only partially dissolves in a polar solvent, whereas in the covalent compound, it dissolves in a non-polar solvent, but only partially dissolves in water.3. The ionic compound at room temperature is solid, while the covalent compound is at room temperature, in the form of a gas or liquid.4. The ionic compound may conduct an electric current, whereas only partially covalent compounds may conduct an electric current.5. The ionic compound can be burnt and odorless, whereas in covalent compounds it can burn and smell (Petrucci, 1990)III. TOOLS AND MATERIALS
      A. Tools
      The tools used in this experiment are test tubes, thermometers, trophy glasses, carbon electrodes, spirit lights, glass splinters, and dropper droppers.A. Ingredients
    The materials used in this experiment were urea, naphthalene, NaCl crystals, Kl, MgSO₄, and Isopropyl alcohols.IV. WORK PROCEDURES

    Comparison of melting point1. A small amount (± 1 - 2) of urea is inserted into the test tube, then inserted a thermometer into the test tube.2. The reaction tube is heated with a spirit light, and the temperature is recorded just as the urea melts. This temperature range is the range of melting points of the urea sample.3. The experiment was done 3 times.4. The same procedure is performed for naphthalene compounds.5. The above procedure is performed for NaCl, KI, and MgSO sen compounds.6. The melting point data is searched from the reference book and compared with the observationsB. Solubility Comparison ..1. The reaction tube is filled with water (tube I) and the other reaction tube is filled with carbon tetrachloride (tube II).2. A small amount of urea is inserted into each tube, then the mixture in each tube is shaken.3. Tubes I and tube II are observed respectively, whether the urea is soluble or not.4. The same procedure is performed for naphthalene, isopropyl alcohol, NaCl, Kl, and MgSO₄. Then observed the solubility of the compound from each tube.C. Comparison of conductivity.1. It contains 50 ml of distilled water into a cup glass. Incorporated carbon electrodes that have been connected to electric current and lamp.2. Repeated the above procedure by adding a few drops of isopropyl alcohol and the observed changes are observed.3. Repeated the same procedure, each added with urea, naphthalene, NaCl, Kl, MgSO₄.V. RESULT AND DISCUSSION
      A. Results
            I. Comparison of melting point

NUMBER	Test step	Observation result
1	A certain amount of urea is fed into the test tube, recorded the exact temperature of the reaction	Experiment I, melting point range: 98 ºC Experiment II, melting point range: 98 ºC Experiment III, melting point range: 98ºC
2	A number of naphthalene are introduced into the test tube, recorded the exact temperature of the reaction	Experiment I, melting point range: 100 ºC Experiment II, melting point range: 100ºC Experiment III, melting point range: 100ºC
3	The melting point data is compared to reference books.	-

            II.  Solubility Comparison

No	Test step	Observation result
1	Urea is inserted in tube I Urea is inserted in tube II	dissolved Not dissolved
2	Naftalena dimasukkan pada tabung I Naftalena dimasukan pada tabung II	Tidak larut Tidak larut
3	Isopropil akohol dimasukkan pada tabung I Isopropil alkohol dimasukkan pada tabung II	Tidak larut Larut
4	NaCl dimasukkan pada tabung  I NaCl dimasukkan pada tabung II	Larut Tidak larut
5	KI dimasukkan pada tabung I KI dimasukkan pada tabung II	Larut Tidak larut
6	MgSO4 dimasukkan pada tabung I MgSO4 dimasukkan pada tabung II	Larut Tidak larut

   III.  Comparison of Conductivity

No	Test step	Observation result
1	Elektroda karbon dimasukkan ke dalam gelas piala berisi akuades	Tidak mengalami perubahan
2	Elektroda karbon dimasukkan ke dalam gelas piala berisi akuades, ditambahkan isopropil alkohol.	Tidak mengalami perubahan
3	Elektroda karbon dimasukkan ke dalam gelas piala berisi akuades, ditambahkan urea.	Tidak mengalami perubahan
4	Elektroda karbon dimasukkan ke dalam gelas piala berisi akuades, ditambahkan naftalena	Tidak mengalami perubahan
5	Elektroda karbon dimasukkan ke dalam gelas piala berisi akuades, ditambahkan NaCl	Mulai menyala pda 7,5 volt dan menggelembung
6	Elektroda karbon dimasukkan ke dalam gelas piala berisi akuades, ditambahkan KI	Mulai menyala pada 12 volt dan menggelembung
7	Elektroda karbon dimasukkan ke dalam gelas piala berisi akuades, ditambahkan MgSO4	Mulai menyala pada 13,5 volt dan menggelembung

  
B. DiscussionIn this experiment, the comparison of melting point, solubility and electrical conductivity is used to compare the composition of ionic compounds and covalent compounds. In determining a compound is an ionic or covalent compound, we can not only look at one of its properties, but we must also look at the whole of those properties, since there are some properties of the ionic compounds belonging to the covalent compound, in order that we can distinguish the two The compound, we do the experiment below:
     1. Comparison of melting point
      From the results of the experiments performed, the result of the range of melting points when urea was introduced was 98 ° C., the results obtained from experiments I, II, and III showing the same results, this is very different from the literature, because according to the literature, Urea melting ranges from 132ºC to 133ºC (Belser, 1987). The range of naphthalene melting point at the time of the experiment was 100 ° C, the results were obtained from experiments I, II, III which showed similar results, whereas in comparison with the literature the results were very different, because in the literature the range of melting points of the naphthalene compound was 80ºC to 82ºC (Belser, 1987). In fact, the difference between experimental results and literature can be caused by several factors, one of which is the inability to investigate the point of melting when the lab works.From the literature obtained data, melting point of NaCl compounds ranging from 801ºC to 804ºC, point of compound KI 681ºC melting point MgSO4 1124ºC (Belser, 1987). Covalent compounds generally exhibit lower melting points than ionic compounds, ie <350 ° C, whereas ionic compounds exhibit a high melting point of> 350ºC - 1000 ° C (Sukardjo, 1990). It can be concluded that urea and naphthalene whose melting point <350 ° C is included in the covalent compound, while KI, MgSO4, and NaCl belong to the ionic compound.2. Solubility ratioFrom the experiments carried out, Urea, NaCl, KI, and MgSO4 when inserted in tube I containing water, soluble, but when naphthalene and isopropyl alcohol are inserted in water, insoluble, this is because water is a polar compound which can only dissolve Ionic-containing compounds. However, there is confusion in the results of this experiment, that is, there is a water-soluble urea, whereas the urea belonging to the covalent compound is not soluble in water, this may be due to the inaccuracy of the practitioner during the experiment. On the contrary, when urea, NaCl, KI, MgSO4, and naphthalene are included in tube I containing carbon tetra chloride, the five compounds are insoluble, this is because the carbon tetra chloride or CCl4 includes non-polar compounds which can only dissolve the covalent compound therein Confusion, namely the dissolution of NaCl, KI, MgSO4 in CCl4, whereas the three compounds are ionic compounds, which should not be soluble in the carbon tetrachloride, this may be due to the inhumanity of the experiments in the experiment.3 Comparison of conductivityFrom the experiment it is known that H2O, Isopropyl alcohol, urea and naphthalene can not conduct electrical current, because they are experimented, the compounds have not changed, so that the compound can be categorized in covalent sukwa, because one of the characteristics of covalent compounds is not Conduct electrical current.Another case with NaCl, KI, MgSO4. In the NaCl at 7.5 volts, it is known that the carbon electrode is lit and bubbles arise, and so does the KI, at 12 volts, the carbon electrode starts to flash and bubbles arise, MgSO4 also experiences the same thing, at 13.5 Volts, start up and bubbles arise. This suggests the three compounds may conduct an electric current, and can be categorized as ionic compounds, because the ionic compounds can transmit an electric current.VI. CONCLUSION1. The melting point of a covalent compound tends to be lower than that of the ionic compound.2. In general, the covalent compound is easily soluble in a non-polar solvent, whereas the ionic compound is readily soluble in water.3. In ionic compounds, can deliver the flow listirik, but the covalent compounds only a part that can conduct electrical current.4. From the experimental results it can be seen that those comprising covalent compounds are isopropyl alcohol, urea, and naphthalene, while those comprising ionic compounds are, NaCl, KI, MgSO4.BIBLIOGRAPHYBelser. A. 1987. The Concept of Modern Physics. Erland. Jakarta.Companion, A.L. 1991. Chemical bond. ITB. Bandung.Sukardjo. 1990. Institute of Chemistry. Rineka Cipta. Yogyakarta.S. Shukri. 1999. Basic Chemistry 1. ITB. Bandung.Sukardjo. 1990. Institute of Chemistry. Rineka Cipta. Yogyakarta.Syarifuddin N. 1994. Chemical Association. Gadjah Mada University Press. Bandung.