Experiment 6 Dissimilarity Between Lectrovalent And Covalent Bond

EXPERIMENT 6 : DISSIMILIRITY BETWEEN ELECTROVALENT AND COVALENT BOND Objectives: To differentiate the properties between covalent compound (either pure covalent or ionic covalent) and electrovalent compound. Introduction Electrovalent compound exist from the arrangement of positive ion and negative ion. In solution, both positive and negative ion was separated due to the existence of water mplecule. If the ion was reacted with another ion and produce more strong compound, the reaction might be more reactive. This effect can be seen from the vigorous formation of sediment and gas released. For the covalent compound, the reactions slowly occur due to the low attractive forces. This compound is hardly to dissolve or solidify in polar solvent. Covalent compound that exist as a gas will produce acid or base solution when dissolve in water such as HCl and ammonia gas (NH3). Water soluble covelent compound which produces ions when it is dissolve in water. Electrovalent compounds are able to conduct electricity either in solution or melted but not in solid form. The ion will attracted to different pole where positive ion will receive electron whereby negative ion will donate electron. Apparatus Test tube, 150 mL beaker, stopper, tube, battery, wire and bulb.

Chemicals NaCl solution, C2H5Br liquid, H2O2 liquid, AgNO3 solution, NaOH solution, phenolphthalein, HCl solution, Na2CO3 solid, Zn/Cu/C electrode, NH4OH solution, ethanol and NaCl solid. Methods PRECIPITATION 1. 3 clean test tubes is prepared and labeled as A, B and C. 2. Test tube A is filled with 5 mL NaCl solution, B with 5 mL C 2H5Br and C with 5 mL H2O2 liquid. 3. 1 mL AgNO3 is added in each test tube. 4. Observed. 5. The precipitation time is recorded. GAS RELEASED 1. 5 mL of NaOH solution is filled in test tube and 2 drops of phenolphthalein is added. 2. 5 mL of HCl solution is filled in another test tube equipped with glass tube. 3. Small amount of Na2CO3 is added in test tube contain HCl. Observe either reaction occur or not. The gas relese can determine by inserting the glass tube into test tube containing NaOH. 4. Any changes is recorded and explained.

ELECTRIC CONDUCTIVITY Setup apparatus as shown as below

1. HCl solution is filled in beaker(half). 2. Zn/Cu electrode is put in the solution. 3. The circuit is witched on when all connection is correct. 4. Observed whether the bulb blink or not, if blink, clear or not. 5. The circuit is switched off, the HCl solution is replaced with NaCl solution, NaOH solution, H2O2 liquid and NaCl solid in ethanol

Results: Precipitation The adding with AgNO3. NaCl C2H5Br H2O2

White precipitate No precipitate No precipitate

Gas released -Pink colour of phenolphthalein become colourless. Electric conductivity HCl(Cu/Zn) -Cu : Bubble is formed -Zn: precipitate formed - the bulb ignition is bright - the solution formed is colourless NaCl(Cu/Zn) -Cu : bubble is formed - Zn : precipitate formed - the bulb ignition is bright - the solution formed is colourless

NaOH(Cu/Zn) -Cu :bubble formed -Zn : precipitate formed -the bulb ignition is bright - solution-bubble formed in the whole solution NaCl in the ethanol(Cu/Zn) -nothing happen or change -the bulb is not give a light

Discussion : For the reaction between Na2CO3 with HCl, the chemical equation is: Na2CO3(aq) + 2HCl(aq)  2NaCl(aq) + H2O(l) + CO2(aq) The gas release is transfer or connect to the another test tube that contain NaOH with added with phenolphthalein. The colour of the solution is change from the dark purple to the colourless. That’s mean the gas that release have the acid properties. That’s we can conclude that the gas release is carbon dioxide, CO2. CO2 is an acidic oxide. In the solution, the ion is move freely, so it can conduct electricity. We take NaCl solution as example, NaCl solution can conduct electric, but NaCl solution cannot conduct electric. Ionic compound is a compound that form fron metal and nonmetal element such as NaCl. NaCl are produced from natrium metal and clorin gas. Ionic compound can conduct electric in a molten form but cannot conduct electric in solid state. Covalent compound are form from electron sharing between two same or different element. Covalent compound cannot conduct electric either in molten or solid state.

Covalent compound is hardly to dissolve in polar solvent such as water. Ionic compound produce an ion that can move freely when it’s dissolve in water. So that, it can conduct electric in melted form. From the result we can see that HCl also can conduct electric although HCl is covalent compound. This is because HCl is strong acid and dissociate freely in water to produce H+ and Cl- ion. Zn electrode that act as anode will attract Clion and OH- ion that negatively charged. OH- ion have high tendency to be discharged because of their position in the electrochemistry series to produce oxygen gas. At cathode, Cu that act as cathode electrode will attract H+ ion that is positively charged and will be discharged to produce hydrogen gas. This process also happened to all experiment that involved ionic compound.

Questions : 1. Describe whether this solution can be electrically conducting or have electrolyte properties: H2S solution, Melt AgCl, HCl solution and melt FeS. - H2S solution will not conduct electric either in the solid state or solution state because they are covalent compound. For melt AgCl and melt FeS, both solution will conduct electric. This is because both compound are in liquid state and are ionic compound, so, the ion in the compound are freely moved and can conduct electric. For HCl, either the solution is covalent compound, it still can conduct electric because they are strong acid and dissociate completely in the water to produce H+ ion and OH- ion.

2. Why NaCl solution can be electrically conducting and solid NaCl are not? - NaCl solution can conduct electric and solid NaCl solution cannot conduct electric because in NaCl solution, the ion is freely moved, so it can conduct electric but in solid NaCl, the ion is not freely moved and just wiggle in the same place. So, it cannot conduct electric. Conclusion - From the experiment we can conclude that all ionic compound can conduct electric in the liquid state but cannot conduct electric in the solid state. But covalent compound cannot conduct electric either in the liquid and solid state.

Reference : 1. http://www.rockwood.k12.mo.us/Lafayette/kupfer/conductivity.htm 2. Chemistry, The Central Science. 11 edition Brown, Lemay, Bursten, Murphy, Pearson Education.